All Done with MirrorsMacbeth's Dagger Discovered

We know nothing whatever about how Macbeth was first performed. Not a shred of evidence survives. It is one of the great Shakespearean mysteries.

But consider the following. Macbeth was Shakespeare’s first and only Scottish play, filled with material guaranteed to interest his new Scottish king, from witchcraft to regicide to James’s descent from Banquo. It was written for performance in a small dark indoor theatre as well as for the huge daylit amphitheatre of the Globe. It was performed at the very moment – I would guess in mid 1606 – when the court was becoming infatuated with an entirely novel kind of theatre, the illusionistic trickery and spectacular sons et lumières of the new masques. Finally, it is full of apparitions and optical illusions – the air-drawn dagger, Banquo’s ghost, witches who vanish like bubbles in water, disappearing cauldrons and brass heads and bloody children, and a parade of phantom kings.

Suppose that it is in part designed as a display of conjuring tricks. Suppose that Shakespeare says to the company, or the company to Shakespeare, ‘We have to keep up with the Joneses and Jonsons. We need to wow the new king with an eye-catching exhibition of special effects. Something full of smoke and mirrors’.

Let us focus on the floating dagger. More than any of the other apparitions, it would immediately remind the audience of a conjuring trick. Legerdemain with daggers and swords was the staple of the street performer. Samuel Rid’s The Art of Jugling (1612), the first handbook of conjuring tricks to appear in England, is packed with them (see, for instance, his entertaining paragraph on how ‘To thrust a bodkin through your head, without any hurt’ – literally the mirror image of the Macbeth scene where Macbeth passes his body through a dagger rather than a dagger through his body without harm).

Reginald Scot in ‘The Art of Juggling Discovered’, which he published alongside his discussion of ‘real’ witchcraft in The Discoverie of Witchcraft (1584), a book with which Shakespeare was closely familiar and often quotes, also lists many dagger tricks, and what is notable about this discussion is that, unlike many Elizabethan clerics, Scot not only refuses to attack such conjuring as a misleading delusion, but defends it precisely as unmagicking the world for the ‘simple’. On the same page of The Discoverie of Witchcraft in which he reveals how ‘To thrust a dagger or bodkin into your guts verie strangely, and to recover it immediatlie’ (it’s done with a false belly made of pasteboard and a bladder of calf or sheep’s blood), he writes that:

so long as the power of almightie God is not transposed to the juggler, nor offense ministred by his uncomlie speach and behaviour, but the action performed in pastime, to the delight of the beholders, so as alwaies the juggler confesse in the end that these are no supernaturall actions, but devises of men, and nimble conveiances, let all such curious conceipted men as cannot afford their neighbours anie comfort…say what they list for this will not only be found among indifferent actions, but such as greatlie advance the power and glorie of God, discovering their pride and falshood that take upon them to worke miracles and to be the mightie power of God.

As long as he lays bare the device, the conjuror’s performance is not only not illicit, it is praiseworthy.

There is no direct precedent for Macbeth’s floating dagger in Rid’s or Scot’s accounts of street performances. But if we move a little up-market, and indoors, to the laboratories of the maguses, it is a different story and other ‘knives of device’ materialise.

Consider for example John Dee’s description of a ‘mervailous’ apparition in the preface to his 1570 translation of Euclid’s Elements of Geometry. Dee was as fascinated as Scot by ‘cozenage’, by illusions of all kinds, and especially by optical illusions. He too passionately wishes to convince his readers that many reported apparitions are not demonic in origin but have ‘natural’ – we would say ‘scientific’ – causes: they are to be classified not as diabolic magic but as what the period called magia naturalis, ‘Natural Magic’ (one of Scot’s purposes was to defend ‘the vertue and power of naturall magike’), and that it is an affront to our reason not to investigate and understand them as such. Dee had good practical as well as intellectual reasons for insisting on the difference between catoptrics and catoptromancy – between science and sorcery – since, like every ‘conjurer’ of the day, he was continually under suspicion of dabbling in devilry. He did spend a good deal of time talking to angels through a magic glass. A mob which did not grasp the category-distinction ransacked his house and library thirteen years later.

As Dee argues, optical science will literally help us to see more clearly, more enjoyably and more rationally:

Perspective, is an Art Mathematicall, which demonstrateth the maner, and properties, of all Radiations Direct, Broken, and Reflected…By this Art…we may use our eyes, and the light, with greater pleasure: and perfecter Iudgement…

We need its help because our senses continually play tricks on us, without any demonic or even human intervention, and it is a matter of intellectual self-esteem to find out why.

We may be ashamed to be ignorant of the cause, why so sundry wayes our eye is decieved, and abused…is it not commodious for man to know the very true cause, & occasion Naturall? Yea, rather, is it not, greatly, against the Soverainty of Mans nature, to be overshot and abused, with thinges (at hand) before his eyes?

Dee goes on to give examples:

a Pecockes tayle, and a Doves nek: or a whole ore, in water, holden, to seme broken. Thynges, farre of, to seeme nere: and nere, to seme farre of. Small thinges, to seme great: and great, to seme small. One man, to seme an Army. Or a man to be curstly affrayed of his owne shadow.

That last phrase is proverbial, but it is hard not to be reminded of Macbeth (‘Hence, horrible shadow’) at this point, and in what immediately follows.

Yea, so much, to feare, that, if you, being (alone) nere a certaine glasse, and proffer, with dagger or sword, to foyne at the glasse, you shall suddenly be moved to give backe (in maner) by reason of an Image, appearing in the ayre, betwene you & the glasse, with like hand, sword or dagger, & with like quicknes, foyning at your very eye, likewise as you do at the Glasse. Straunge, this is, to heare of; but more mervailous to behold, then these my wordes can signifie. And neverthelesse by demonstration opticall, the order and cause therof, is certified: even so, as the effect is consequent. Yea, thus much more, dare I take upon me, toward the satisfying of the noble courrage, that longeth ardently for the wisedome of Causes Naturall: as to let him understand, that, in London, he may with his owne eyes, have prove of that, which I have sayd herein. A Gentleman, (which, for his good service, done to his Countrey, is famous and honorable: and for skill in the Mathematicall Sciences, and Languages, is the Od [unique, remarkable] man of this land. &c.) Even he, is hable: and (I am sure) will, very willingly, let the Glasse, and prove be sene: and so I (here) request him: for the encrease of wisedome, in the honorable: and for the stopping of the mouths malicious: and repressing the arrogancy of the ignorant.

‘Come, let me clutch thee: I have thee not, and yet I see thee still.’ Is not this Macbeth’s air-drawn dagger to a T, even down to the detail of the lone observer ‘giving back’ at the dagger’s sudden appearance? Isn’t this too much of a coincidence to be mere coincidence? But I know of no edition of or commentary on Macbeth which cites this description as at least an analogue and perhaps even the source of the scene.

Is this just yet another of those descriptions of fanciful and fantastic machines of which there are so many in Renaissance writings and drawings – like Leonardo’s, say – constructed out of hearsay (‘At Alexandria, the ancients are reported to have had…’, ‘It is said that in Prague, the Emperor has…’, and so on) but which did not exist, and if they had existed would not have worked? Even if it is, and Dee’s ‘mervailous glass’ existed only on his page, it (or one like it) could of course still have caught Shakespeare’s imagination and suggested the form of Macbeth’s hallucination. But how much more interesting all this is if this was something Shakespeare could have stood in front of and foined at – ‘Straunge, this is, to heare of; but more mervailous to behold’ – and then imagined Burbage using on stage. The King’s Men stayed in Mortlake for an extended period at the end of 1603, avoiding the plague, and Mortlake was a tiny village, a straggle of houses along the Thames towpath, dominated by Dee’s mansion and laboratories. If Shakespeare and Dee were not already acquainted, I find it hard to believe that they would not have become so on this occasion. Dee was famously generous, keeping an open house, and eager to show off his library and devices to visitors.

There are in fact very good reasons for supposing that Dee’s glass did exist. The whole force of his argument depends after all on his exempla being irrefutably real, even familiar, objects, ‘things at hande’ as he describes them – the iridescence of a peacock’s neck, an oar appearing bent in the water – rather than fantasies; and he strongly emphasises that this is no magic mirror in a fairytale, but that he can take his readers to it and stand them in front of it, here and now, in London. He positively urges them to call his bluff if they are sceptical. In fact he even provides the address: in the margin appear the letters ‘S.W.P.’. I take this to be Sir William Pickering (1516–1575), and that the house is Pickering House on St Mary Axe just east of Bishopsgate in the parish of St Andrew Undershaft. Dee knew Pickering well: he had tutored him in Paris in 1550, while Dee was dazzling the French intelligentsia with his lectures on Euclid and Pickering was the English Ambassador, and their friendship persisted. Pickering played an important role in Dee’s early career – he acted as a go-between between Dee and the great mathematician Peter Ramus for instance – and especially in regard to scientific instruments. He kept up his interest in applied science. In his fifteen years of quiet retirement in London after ‘his good service, done to his Countrey’ as a diplomat he seems to have partly occupied himself as an amateur of science: he left his collection of instruments, including globes and compasses, to William Cecil, Lord Burghley, the queen’s most senior counsellor.

In fact Dee subsequently acquired (or retrieved: he had all the optical skills to manufacture it) the mirror he describes and thereafter its effects were even more ‘provable’. Indeed, its display became one of his most celebrated turns, more or less his trademark. I think that this – rather than one of his magical glasses, as so many scholars have assumed – was the glass which the Queen found so fascinating and came to view at Dee’s Mortlake laboratory in 1575, and which the Emperor asked him to exhibit in Prague nine years later.

But there is in any case plenty of other evidence for the existence of such devices in the later sixteenth century. They were part of – indeed they were the culmination of – Renaissance intellectuals’ fascination for what was in effect a whole sub-science within optics, the discourse on the theory and practice of producing ‘artificial spectres’. They were enthralled by accounts by classical authors of how the priests of ancient Egypt had kept the population in awe by producing floating and disembodied apparitions in their temples. At Tarsus, for example, according to Photius (Patriarch of Constantinople, writing in the eighth century from second-century sources):

In a manifestation which one must not reveal…there is seen on a wall of the temple a mass of light, which appears at first at a very great distance. It is transformed, while unfolding itself, into a visage evidently divine and supernatural, of an aspect severe, but with a touch of sweetness. Following the teachings of a mysterious religion, the Alexandrians honour it as Osiris or Adonis.

But Apuleius’s was the most celebrated account:

Thou shalt understand that I approached neere unto Hell, even to the gates of Proserpina, and after that, I was ravished throughout all the Element, I returned to my proper place: About midnight I saw the Sun shine, I saw likewise the gods celestiall and gods infernall, before whom I presented my selfe, and worshipped them.

Adlington’s 1566 translation of The Golden Ass, quoted here, was enormously popular, and Shakespeare knew it well: its influence is clear in his work, particularly in A Midsummer’s Night Dream, Othello and Much Ado About Nothing.

Renaissance enthusiasts for these optical phenomena can be divided into two main camps (and the difficulty for modern commentators is that some of them – notably Dee himself – belonged to both camps at once, apparently without any sense of inconsistency). The first camp (let us call them ‘the hermetists’), the one to the study of which Frances Yates devoted her life, believed that the Egyptians could actually draw the spirits down from their spheres, and that they would be able to do so themselves once they had thoroughly digested the works of the Egyptian magus Hermes Trimegistus. The other camp (let us call them ‘the natural magicians’), the one which is my main focus here and amongst whose productions I am picturing Macbeth, was of a more sceptical turn of mind. They had read or heard of Hero of Alexandria’s ‘discovery’ of the devices used by priestly con-men in ancient Egypt, and they thought such shows were all done with mirrors, to hoodwink the vulgar. Cornelius Agrippa (whose Three Books of Occult Philosophy of 1531 were also widely read and were also in Dee’s library) reported Aristotle’s claim that certain eye-defects can result in one seeing one’s own image floating in midair and then went on to describe how, similarly:

by the artificialness of certain looking-glasses, may be produced at a distance in the Air, beside the looking-glasses, what images we please; which when ignorant men see, they think they see the appearances of spirits, or souls; when, indeed, they are nothing else but semblances kin to themselves, and without life.

The pressing question for this group was then of course what kinds of looking glasses would produce such effects? Hero had described a pair of plane mirrors, angled at 30°, which made the image of a statue, hidden and illuminated in a corner, appear in the middle of a shadowy temple. But it is hard to see how that would have been very effective in producing an image actually afloat in midair. Increasingly, the spherical concave mirror became the favourite candidate and the one on which practical attempts to reproduce the effect centred.

The classical theorists of optics had been fascinated by the properties of concave mirrors and they passed their fascination on to the great Arab scientists of the Cairo Renaissance, and especially to Al-Hazen (c. 965–1039), who gave a complete account and experimental proof of the laws of reflection from curved mirrors. From the Arabs this knowledge passed directly to that extraordinary founder of the modern physical sciences, Roger Bacon (c. 1214–1292?), of whom it was later said that, ‘To him, and apparently to him only, among all the inquiring spirits of the time, were known the properties of the concave and convex lens’. Bacon described how to produce special effects with concave mirrors in carefully precise and workmanlike terms. In his Opus maius he says that by artificial condensation of the air and an arrangement of mirrors, ‘appericationes’ can be produced to terrify infidels and enemies of the realm. Bacon’s theories and instructions, either directly in his own writings or through associates like Vitello and Peacham, in effect constituted the theory of optics from the end of the thirteenth century until Shakespeare’s time. Indeed a remarkably direct line runs from Bacon’s Natural Magic mirrors to those of Dee’s day. Bacon was celebrated and thoroughly studied by Elizabethan scientists and by Dee in particular, who took him as the epitome of the true philosopher. He owned many Bacon manuscripts – more than those of any other author in fact – and annotated them heavily. His copy of Scientia perspectiva is especially heavily scribbled on. He would have known that optics were central to Bacon’s definition of Natural Magic, providing his clearest examples, and that the concave mirror in turn played a central role in his optics. Indeed, it was from Bacon that he derived the distinction between the ‘natural’ and demonic forms of magic which is so crucial to his entire oeuvre and to my argument. He published a book in defence of him, the now lost Speculum unitatis, sive Apologia pro Fratre Rogerio Bacchone Anglo of 1557, in which he says that his marvelous achievements and devices were the products of nature and mathematics, not ‘commerce with demons’.

The reason he no doubt felt particularly obliged to defend Bacon – and thus indirectly to defend his own practice – was that alongside Bacon the scientist, a quite different Bacon haunted the sixteenth century, the Bacon of the popular imagination, dealer with demons, archetypal embodiment of the spirit-conjuring magician, and he too was a mirror master. A pamphlet entitled The Famous Historie of Fryer Bacon went into numerous editions, although none earlier than 1627 survives, and Robert Greene – whose work Shakespeare certainly followed with close attention – transformed the pamphlet into a play which was a great hit and also went into numerous editions. In his Friar Bacon and Friar Bungay – unlike the pamphlet – Bacon has nothing of the scientist about him. He is entirely a sorcerer and the ‘glasse prospective’ in which, disastrously, he allows two young scholars to look far away into Suffolk (they see their fathers fighting and turn murderously on one another) is a true magic mirror, not a telescope. Probably written in 1589 and published in 1594, it had a successful revival – a court revival – not long before Macbeth, and I take it that Shakespeare was cashing in on its success when he gave the eighth king a similar glass in Act IV. Greene’s play also features Bacon’s other most famous device, the talking brass head, and this too makes its appearance in Macbeth.

By Dee and Shakespeare’s time there was thus an extensive literature on how to float artificial spectres in midair with the aid of concave mirrors, and the technology was advancing rapidly. The great breakthrough had come with the invention of the silvered glass mirror by the Venetians at the beginning of the sixteenth century. Earlier mirrors, from the classical period onwards, had been of polished metal and any image they produced was fuzzy. Now, startlingly life-like and accurate illusions were possible. The Italians set the pace but we have perhaps not yet sufficiently realised how advanced the English rapidly became, with interesting cultural effects, in the production of mirrors and lenses and prisms. There is now general scholarly agreement that Thomas Hariot invented a form of the telescope; and, importantly, Elizabeth and her advisors rapidly grasped the potential, including the military potential, of these devices. In 1570, William Cecil – the same William Cecil who was bequeathed Pickering’s instruments – commissioned a report on uses of mirrors and lenses. It identified Dee, along with Thomas Digges, as England’s leading experts.

So when Dee acquired or manufactured his ‘mervailous glass’, this was no unique breakthrough, ex nihilo. He was very well aware that such objects were well known on the Continent, and he was working hard to keep up with the Italians (and, before long, the Dutch). It sounds to me as if, in writing his ‘Præface’, he had open on his desk his copy of Giambattista della Porta’s Magiae naturalis, sive de miraculis rerum naturalium. This work was one of the bestsellers of the sixteenth century. A compendium of Natural Magic tricks, toys and marvels, it was such an immediate hit when it came out in four books in 1558 that it was rapidly re-issued in at least five more Latin editions and translated into Italian, French and Dutch (and also, so della Porta claims, into Spanish and Arabic) during the next decade. In 1589 he published a hugely expanded version, in twenty books, and this too was read throughout Continental Europe, and was constantly reprinted in new editions in Latin, and in the vernacular languages, now including German. But no English translation appeared until 1658, and this may account for its surprising neglect by historians of English Renaissance culture and of Shakespeare. Reginald Scot knew it however, and cites it in his Discoverie. I find it hard to believe that Shakespeare would not have known of it, given his remarkably broad knowledge of Italian culture, and especially of Italian drama: della Porta was a celebrated playwright as well, and at least as early as the first decade of the seventeenth century his plays were being translated into English: they became quite a cult at Cambridge.

After an introductory disquisition ‘Of the Causes of Wonderful Things Wherein are searched out the causes of things which produce wonderful effects’, della Porta takes his readers on a tour of such matters as ‘The Wonders of the Load-Stone’, artificial fires, how to beautify women, invisible writing, and in Book 17, in some of the most excited prose in the book, ‘Strange Glasses’. Following ‘merry sports with plain glasses’, where he describes inter alia how to construct a ‘theatre of mirrors’, he comes to ‘Divers operations of Concave-Glasses’ and explains that, compared to plane mirrors, ‘the operations of Concave-glasses are far more curious and admirable, and will afford us more commodities.’ First of all, you must discover the mirror’s ‘point of inversion’.

Then many spectacular and entertaining effects, innocent and not so innocent, become possible.

When you have found the point of Inversion, if you will…Set your head below that point, and you shall behold a huge Face like a monstruous Bacchus, and your finger as great as your arm: So women pull hairs off their eyebrows, for they will show as great as fingers. Seneca reports that Hostinus [della Porta is referring to the Naturales Quaestiones I, 16, where there is a general discussion of how apparitions are produced] made such Concave-Glasses, that they might make things shew greater: He was a great provoker to lust; so ordering his Glasses, that when he was abused by Sodomy, he might see all the motions of the Sodomite behind him, and delight himself with a false representation of his privy parts that shewed so great.

All this is fun, could no doubt be put to ‘theatrical’ use, and perhaps was. A set of these arranged with various degrees of distortion as a theatre of mirrors would have been an early version of the Hall of Mirrors of the modern fun-fair (one of Dee’s biographers suggests that this is what Elizabeth had come to play with at Mortlake). But della Porta then proceeds to describe something much more spectacular, ‘To make an Image seem to hang in the Air, by a Concave-Glass’:

This will be more wonderful with the segment of a circle, for it will appear farther from the Glass. If you be without the point of Inversion, you shall see your head downwards. That with fixed eyes, and not winking at all, you may behold the point, until it comes to your very sight: For where the Catherus [a line perpendicular to the surface] shall cut the line of reflection, there the species reflected will seem almost parted from the Glass: the neerer you are to the Centre, the greater it will be, that you will think to touch it with your hands: and if it be a great Glass, you cannot but wonder; for if any man run at the Glass with a drawn sword, another man will seem to meet him, and to run through his hand.

The image of the dagger, of l’homme armé, again. When Dee encountered or manufactured such a glass, he knew that the standard way of demonstrating its effects was with a sword or dagger. (A swordsman also appears in illustrations of the other main method of producing three-dimensional floating images, the cylindrical mirror.) When Shakespeare wrote his scene, he knew that many ‘of the wiser sort’ in the audience would have been instantly reminded of that well-known mirror trick, the mysterious floating dagger, and that he was thus invoking the whole tradition of Natural Magic, and its message that what the vulgar take to be demonic apparitions are often simply conjuring tricks.

Would it have actually worked, this remarkable device, which, so Dee and della Porta claim, produces not just a strange reflection, but what we would now call a ‘virtual image’, hologram-like, afloat in midair, ‘that you will think to touch it with your hands’? Certainly. I have a small horizontal version of the device on my desk beside me as I write. It is elegantly simple. It has no moving parts and no external power source; no lasers have been used in producing it, as with modern holograms. It is simply a highly polished concave mirror covered by a dome of black plastic with a small circular opening in the centre which conceals the mirror, and above the opening floats the three-dimensional image of a small toy dagger. The effect is uncannily solid and lifelike. Visitor after visitor starts back when they reach out to touch it and find they have it not.

Sir David Brewster, expert adviser to Sir Walter Scott in such matters, inventor of the stereoscope and the kaleidoscope, Vice-Chancellor of the University of Edinburgh, creator and President of the British Association for the Advancement of Science, and one of the great optical scientists of the nineteenth century, provides an especially lucid and practical explanation of how and why the concave mirror works in his Letters on Natural Magic of 1832. His account is also a clear instance of the later history of Natural Magic optics and of one of its chief ideological functions, the demystifying of priestly magic:

the monarchs and priests of ancient times carried on a systematic plan of imposing upon their subjects – a mode of government that was in perfect accordance with their religious belief: but it will scarcely be believed that the same delusions were practised after the establishment of Christianity, and that even the Catholic sanctuary was often the seat of these unhallowed machinations.

Four hundred years after Dee, Brewster is still part of the sceptical tradition of ‘discovering’ – uncovering, exposing – magical illusions (his book’s title is no doubt a deliberate reference to his Renaissance predecessors and perhaps specifically a tribute to della Porta), but now in a much more aggressively anti-clerical – and specifically anti-Catholic – vein (Brewster was also a pillar of the Kirk). ‘The prince, the priest, and the sage, were leagued in a dark conspiracy to deceive and enslave their species.’ Although acoustics and hydrostatics provided the basis for many tricks –

There can be little doubt that the most common, as well as the most successful, impositions of the ancients were of an optical nature, and were practised by means of plane and concave mirrors…The concave mirror is the staple instrument of the magician’s cabinet, and must always perform a principal part of all optical combinations. In order to be quite perfect, every concave mirror should have the surface elliptical, so that if any object is placed in one focus of the ellipse, an inverted image of it will be formed in the other focus. This image, to a spectator rightly placed, appears suspended in the air, so that if the mirror and the object are hid from his view, the effect must appear to him almost supernatural.

Brewster then gives a precise and practical description of how to do it.

The method of exhibiting the effect of concave mirrors most advantageously is shown in Fig. 3, where CD is the partition of a room [in my story, one converted into a small indoor theatre] having in it a square opening ELF, the centre of which is about five feet above the floor. This opening might be surrounded with a picture-frame, and a painting which exactly filled it might be so connected with a pulley that it could be either slipped aside, or raised so as to leave the frame empty. A large concave mirror MAN is then placed in another apartment, so that when any object is placed at A, a distinct image of it may be formed in the centre of the opening ELF. Let us suppose this object to be a plaster cast of any object made as white as possible, and placed in an inverted position at A. A strong light should then by thrown upon it by a powerful lamp, the rays of which are prevented from reaching the opening EF.

(The King’s Men would not have had a lamp of the kind Brewster has in mind, but lens systems which could powerfully focus candlight were being imported from the Italian theatre.)

When this is done, a spectator placed at O will see an erect image of the statue at B the centre of the opening – standing in the air, and differing from the real statue only in being a little larger, while the apparition will be wholly invisible to other spectators placed at a little distance on each side of him.

Brewster goes on to give further examples of scary effects.

It has long been a favourite experiment to place at A a white and strongly-illuminated human skull…but a more terrific effect would be produced if a small skeleton, suspended by invisible wires, were placed as an object at A. Its image suspended in the air at B…could not fail to astonish the spectator.

But he saves his most frightening example to last, one that he could have found in the Mémoires récréatifs (1831) of the great French expert on phantasmagoria Étienne Robertson:

A deception of an alarming kind, called the Mysterious dagger, has long been a favourite exhibition. If a person with a drawn and highly-polished dagger, illuminated by a strong light, stands a little farther from a concave mirror than its original focus, he will perceive in the air between himself and the mirror an inverted and diminished image of his own person with the dagger similarly brandished: if he aims the dagger at the centre of the mirror’s concavity, the two daggers will meet point to point, and, by pushing it still farther from him toward the mirror, the imaginary dagger will strike at his heart.

Once again, this sounds strikingly close to Macbeth’s situation (although the direction of dagger is once again reversed).

But here we should pause. If Shakespeare is not only imagining the mysterious dagger deception, as he had read of it in Dee’s ‘Præface’ and/or seen it at Mortlake, but is actually contemplating using it on stage, a major difficulty at once presents itself. Such an arrangement would make the actor himself the spectator, and the only spectator: no one in the audience could see it. Brewster’s next paragraph explains one way around the difficulty. For the dagger to strike at the spectator’s heart –

it is necessary that the direction of the real dagger coincides with a diameter of the sphere of which the mirror is a part; but if its direction is on one side of that diameter, the direction of the imaginary dagger will be as far on the other side of the diameter, and will aim a blow at any person [or of course simply be visible to any person] who is placed in the proper position for receiving it. If the person who bears the real dagger is therefore placed behind a screen, or otherwise concealed from the view of the spectator who is made to approach to the place of the image, the thrust of the polished steel at his breast will not fail to produce a powerful impression. The effect of this experiment would no doubt be increased by covering with black cloth the person who holds the dagger, so that the image of his hand only should be seen.

Such an arrangement at least allows for one spectator as well as the actor to see the thing, but only one: it will be ‘wholly invisible to other spectators placed at a little distance on each side of’ that spectator. On this account, there appears to be no possibility of a performance before an audience, even a small one. But, on the occasion which I am attempting to reconstruct, is that really necessary? Think of a Macbeth which is more like a masque than a public amphitheatre performance and you at once have a theatrical form whose effects are designed for, and whose sightlines run back to one pair of eyes alone: the king’s. As Stephen Orgel puts it in The Illusion of Power,

After 1605, when perspective settings were introduced – and they were used only at court or when royalty was present – the monarch became the centre of theatrical experience in another way…In a theater employing perspective, there is only one focal point, one perfect place in the hall from which the illusion achieves it fullest effect. At court performances this was where the king sat.

In the ideal court performance which I imagine, only the king (or perhaps two kings) receives the full effect. The other members of the audience see what any audience usually sees: a man imagining a dagger afloat in what they know is thin air. A nice form of visual flattery.

But in any case there was a further way of widening the apparition’s visibility, one which in fact would actually increase its terrific effects.

If the opening EF is filled with smoke rising either from a chafing dish, in which incense is burnt, or made to issue in clouds from some opening below, the image will appear in the middle of the smoke depicted upon it as upon a ground, and capable of being seen by those spectators who could not see the image in the air. The rays of light, in place of proceeding to an eye at O, are reflected as it were from those minute particles of which the smoke is composed, in the same manner as a beam of light is rendered more visible by passing through an apartment filled with dust or smoke.

Brewster thinks that this was what so impressed Benvenuto Cellini in one of the most famous and vividly described of all public performances of an ‘artificial spectre’ show in the Renaissance, the episode in the Coliseum when, after large quantities of perfumes had been burned, ‘There appeared several legions of devils’, terrifying the spectators out of their wits:

it is impossible to peruse the preceding description without being satisfied that the legions of devils were not produced by any influence upon the imaginations of the spectators, but were actual optical phantasms, or the images of pictures or objects produced by one or more concave mirrors or lenses. A fire is lighted, and perfumes and incense are burnt, in order to create a ground for the images, and the beholders are rigidly confined within the pale of the magic circle. The concave mirror and the objects presented to it having been so placed that the persons within the circle could not see the aërial image of the objects by the rays directly reflected from the mirror, the work of deception was ready to begin. The attendance of the magician upon his mirror was by no means necessary. He took his place along with the spectators within the magic circle. The images of the devils were all distinctly formed in the air immediately above the fire, but none of them could be seen by those within the circle. The moment, however, that perfumes were thrown into the fire to produce smoke, the first wreath of smoke that rose through the place of one or more of the images would reflect them to the eyes of the spectator, and they could again disappear if the wreath was not followed by another…Although Cellini declares that he was trembling with fear, yet it is quite evident that he was not entirely ignorant of the machinery which was at work, for in order to encourage the boy, who as almost dead with fear, he assured them that the devils were under their power, and that ‘what he saw was smoke and shadow’.

Such a show of ‘fumo e ombra’ is pretty much what the King’s Men’s Special Effects expert was after, in my account.

The technique of projecting frightening images onto smoke-clouds – literal ‘smoke and mirrors’ – was evidently well developed, and if there was one thing that the Assistant Stage Manager of an English acting company could certainly do, it was to produce large quantities of stage-smoke to order. The technique had been well known for centuries. It was widely used in the theatre of Shakespeare’s day, for example in Marlowe’s Dr Faustus, which had been revived onstage just as Shakespeare was creating Macbeth. And spectacular new applications – especially in conjunction with new kinds of lighting effects – were competing with one another for court attention in the new masques.

I have no idea whether the King’s Men actually used a concave mirror (or a camera obscura, or a proto-magic lantern) in an indoor performance of Macbeth. If I had to rein in my flights of fancy, I would guess that the most probable scenario is that Shakespeare wrote the play as it were subjunctively, in the ‘what if’ mode. He knew of, and had probably seen, some of the exciting new illusionistic devices that were around. He pictured their theatrical possibilities and had them vividly in his mind when he wrote Macbeth. But he also knew that there were practical difficulties – the size of mirrors available, narrow angles of view, above all the intensity of the available light sources – which made the current versions hard to deploy effectively in a theatre, so he wrote the play in a way that would permit their use when and if that became possible.

But whether or not it was used on such and such a night in this room or that at Richmond or Hampton Court or Greenwich, I think I have established that Dee’s ‘mervailous glass’ is present in the text. If this is so, it is an interesting addition to the study of the sources of Macbeth: no one, to my knowledge, has suggested such an origin for the floating dagger before. It is a potentially important contribution to the history of special effects and stage illusions on the English stage. It establishes a possible link between John Dee and Shakespeare, important because, among other things, it provides evidence of Shakespeare’s direct acquaintance with the discourses of Natural Magic, which were playing a major role in the growth of the modern scientific world view.

All this may be of interest to historians. But does it make any difference to the way in which we actually read or perform Macbeth? Everything in our interpretation of the play turns on how we understand its presentation of demonic magic. Ever since the Romantics, Macbeth has been read as a profound, and perhaps personal, vision of the reality of evil spirits, almost Manichaean in its portrayal of the Powers of Darkness powerfully and directly intervening in the world. This seems to me quite wrong. It does not correspond to such a vision anywhere else in Shakespeare – the only parallel, the Ghost in Hamlet, is a profoundly ambiguous figure – and it would make Macbeth a deeply atavistic and nasty enterprise. Did Shakespeare really set about whipping up witch-phobia in his audience when every enlightened contemporary was moving in the opposite direction? And where in Macbeth is there evidence of demons’ powers to intervene directly in human affairs? There is one obvious response to this question, and at first sight it seems to settle the matter: in the Hecate scenes, of course. To ensure that we have no doubts about the reality of evil spirits, Shakespeare has placed the Goddess of Witchcraft in the centre of the play and then made her make it clear that she is in full command of the events of the play. But he didn’t. We are now as sure as we can be that the Hecate scenes are a later interpolation, almost certainly written by Middleton some ten years after (the song in the first of them is taken from Middleton’s The Witch, probably written c. 1615), with Shake-speare either dead or dying and unable to protest against the crude damage done to his play. Remove Hecate from the text and what is left of supernatural spirits? A group of disheveled old ladies with comically distasteful lunch habits who certainly have what the Scots call Da Shealladh, two sights or the second sight, but are more likely to remind a Jacobean audience of the Cunning Folk, low grade hexers, spiteful curdlers of milk and killers of swine and tormenters of sailors’ wives, than of powerful and effective demons. They prophesy but they have no powers to work serious maleficence. They don’t actually do anything especially wicked. And apart from the sisters, all we have is a series of phantasmal hallucinatory visions the reality-status of which Shake-speare is careful to make extremely ambiguous.

To put magic on stage is always in some measure to ‘discover’ it in the sixteenth-and seventeenth-century sense of the word, for if actors can plausibly fabricate it, night after night, how much other supposed magic may be produced by the same means? And this was especially true at this particular moment, when the Jesuits for example were being widely ‘discovered’ for deluding the masses with supposed exorcisms (often using mirrors, incidentally) which were pure theatrical contrivance (Shakespeare had been reading the most influential critic of such ‘Popish Impostures’, Samuel Harsnett, with great care). But when, in addition to simply letting theatricality do its own work, you specifically and deliberately include in your performance reference to one of the most well-known demonstrations of Natural Magic of your day, you encourage your audience to nudge their neighbours and say, ‘Wait a minute. I know how that’s done. I heard about the Queen going to Mortlake to see a trick magic dagger like that.’

I believe that my theory strengthens the argument that there is a strong ‘Sadducean’ tendency in Macbeth. Sadduceans – sceptics about the reality of spirits – had two main kinds of explanation for the majority of supposed spirit-sightings, an internal one and an external one. They were either disorders of the senses, caused by anything from booze to eye-defects to phobias and overactive imagination (for, as Theseus observes, ‘in the night, imagining some feare, How easie is a bush suppos’d a Beare?’ – or a bugbear); or they were actual phenomena, produced either naturally (Brocken spectres, will-o’-the-wisps) or artificially, to entertain (jugglers) or to deceive (Jesuits). The first kind of explanation is prominent in Macbeth: the apparitions which Macbeth sees are ‘paintings of his fear’ according to Lady Macbeth, and even her more superstitious husband eventually decides that both the floating dagger and the ghost of Banquo are merely fantastical, twitches of his over-stretched nerves. But my argument is that the second category of Sadducean explanation – trickery, legerdemain – is also prominent in Macbeth, by intertextual reference to Natural Magic texts or – if you can work out a way of using marvellous glasses onstage – by actual demonstration.

Is Shakespeare saying to James I and VI, author of the Dæmonologie (whose explicit purpose was to refute the ‘damnable’ Reginald Scot and other sceptics and which Shakespeare had read carefully), ‘Look, all that stuff about witches flying around on broomsticks and ghosties and ghoulies may have gone down alright in benighted Scotland. But this is the seventeenth century and this is England. These things are mainly the result of brainstorms or smoke and mirrors, sire. Mere smoke and mirrors.’