The heart, the soul, the engine of the philosophical toy is the afterimage, virtual reality itself.

One could say that the whole of cinema is build upon the discovery that we can see things that aren't there. If I remind you of the obvious, it is because the great cinematic engine of 24 frames per second and to an even greater extent video, which hides even its frames in magnetic dust, effaces the traces of its own production, reifying motion in the best capitalist tradition.

Thus we must go back to very first philosophical toys to recapture this magical sensation. It was discovered at the beginning of the 19th century that our eyes were not simply a blank screen like the dark chamber of the camera obscura onto which the exterior was projected, but that is was actually possible to experience the presence of sensation in the absence of stimulus. This turned the whole philosophy of vision upside down. Vision was not something fixed and immutable in the world that enters the mind though the eye but could be created in the mind and ‘projected’ back onto the world.

This concept of interior vision, of a cinema of the mind is so far reaching that even today its repercussions have perhaps still to be experienced in cinemas of the future.

And yet it is a principle that can be demonstrated with the simplest of all cinematic apparatuses, the two-frame animation or alternation.

SPIN ME!
The Thaumatrope was invented in 1825 by John A. Paris who explained the theory behind the afterimage in "Philosophy in Sport Made Science in Earnest; Being an Attempt to Illustrate the first Principles of Natural Philosophy by the Art of Popular Toys and Sports" (London 1827). Its the first reference I can find to the concept of the "philosophical toy" but here I refer also to another 19th century source, an article that appeared in 1853 by Charles Baudelaire, "The Philosophy of Toys". Already this suggests that toys themselves have a philosophy of their own.
WHERE IS ITS SOUL?
Toys spark off in the imaginative life of the child not simply scientific discovery but a metaphysical yearning, cumulating in the child's search for the soul of his toy which results inevitably in its destruction, "But where is its soul? This moment marks the beginnings of stupor and melancholy." (1) And among the toys that Baudelaire describes is the Phenakistiscope.

"Apply your eye at the level of the little windows, and spin the cardboard discs rapidly. The speed of rotation transforms the twenty openings into a single circular opening, through which you see twenty dancing figures reflected in the mirror, all exactly alike and executing the same movements with a fantastic precision. Each little figure has availed himself of the nineteen others. On the card the figure spins and its speed makes it invisible; but in the mirror, seen through the revolving windows, it is motionless, executing on the spot all the movements that are distributed between all twenty figures. The number of pictures which can thus be created is infinite." (2)

Perhaps this child’s search for the soul of the toy, "forcing it to continue its mechanical motions sometimes in the opposite direction" is also a search for the origin of its "life", the metaphysics of its marvelous motion. Where is it? The child can slow down the Phenakistiscope, the dancers stop dancing, he speeds it up they resume the dance. Forwards, backwards, so mysterious. It is this not taken for granted motion, its uncertainly and immanent collapse that, rather than being a hindrance is I believe essential to the magic of these toys.

THE MAGICIAN AND THE DECEIVED
It is ironic that David Brewster, one of the greatest of the 19th century inventors of philosophical toys, the stereoscope and the kaleidoscope was a Scottish Calvinist. Cold and gray, it is the dourest, least pleasure loving of religions. His aim was the debunking of optical magic though which he believed other religions namely Catholicism held their sway over impressionable minds. However according to Jonathan Crary, "his implied program of democratization and mass dissemination of techniques of illusion, simply collapsed that older model of power onto a single human subject, transforming each observer into simultaneously the magician and the deceived." (3) To which I reply, what an extraordinary and remarkable achievement.

If I have not extended consideration of the stereoscope and kaleidoscope here, it is because they do not properly fall into the realm of the moving image. However one might consider those strange creatures, Duchamp’s Rotoreliefs, where a sound making machine, the phonograph spinning at 78 rpm is used to create the illusion of three dimensional space to be a cinematic counterpart. For cinemas that traffic in more and less than two dimensions see:
AMNESIAC CINEMA and HYPNOGOGIC CINEMA.
However the very nature of the afterimage turns each viewer into the magician and the deceived and opens up a whole realm of possibilities around this concept of a cinema that exists only in the mind’s eye. We enter the realm of science fiction, Gibson’s "Neuromancer" where cyberspace is a consensual hallucination is but one example.

In 1866 J.H. Brown published a book called "Spectropia" expressly to debunk the existence of ghosts by explaining that they were produced by afterimages. (4) See:

While a hundred and thirty years later, Raul Ruiz told the following tale in his book "The Poetics of Cinema", "What is interesting is the suggestion that we can use intervene to provoke virtual images by the brain’s compensatory mechanisms. A group of people who are involved in manufacturing special effects for the Lucas Company in Hollywood discussed with me the possibility of making "personalized" animated films exclusively out of such images. The principle obstacle is that the brain needs twenty or thirty seconds to process the first image, but once the first image is reconstituted the others can run off in animated series using the same basic pattern. We went further, though, and from these flux-images we imaged film sequences in which abstract animated images would provoke different responses in each of us. Each spectator would watch a different 3D film than his neighbor, for each would have visual uncertainties (fluxes) of his own." (5)

(1) Baudelaire, Charles "The Philosophy of Toys" Essays on Dolls (trans) Idris Parry and Paul Keegan. London, Syrens, 1994, p. 24

(2) Ibid. p.21

(3) Crary, Johnathan Techniques of the Observer MIT 1990, p.133

(4) Brown, J.H. Spectropia or Surprising spectra illusions: showing ghosts everywhere, and of any color London, Griffith and Farran, 1866

(5) Ruiz, Raul The Poetics of Cinema France Éditions Dis Voir p.p.
42-43