"My little Animal, after you have mentally separated each little visible body into an infinity of little invisible bodies, you are to imagine that the infinite Universe is composed of nothing but these infinite atoms which are very solid, very incorruptible, and very simple. Some are cubes, some parallelograms, some angular, some round, some pointed, some pyramidal, some hexagonal, some oval, and all act differently according to their shape. And to prove this, place a very round ivory ball upon a very smooth surface; and at the slightest movement you give it, it will be a half-quarter of an hour before it stops; to which I add that if it were as perfectly round as some of the atoms of which I speak, it would never stop. Then if art is capable of inclining a body to perpetual motion, why should we not believe that Nature can do it? It is the same with other shapes; one, like the square, demands perpetual rest; others, a movement sideways; others, a half-movement like palpitation. When the round, whose nature is to move, joins with the pyramidal, it perhaps makes what we call fire, because fire not only moves without resting but pierces and penetrates easily. Moreover, fire produces different effects according to the size and quantity of the angles where the round shape is joined; the fire of pepper is different from the fire of sugar, the fire of sugar from that of cinnamon, the fire of cinnamon from that of cloves, and this in turn from the fire of a faggot. Well then, fire, which is the constructor and destructor of the parts and of the whole of the Universe, gathers into an oak the quantity of shapes necessary for the composition of that oak. But, you will say, how could mere chance collect in one place all the things necessary to produce this oak? I reply that it is not extraordinary that matter so placed should make an oak, but it would have been very much more marvellous if an oak had not been formed when matter was thus disposed. Had there been a little less of certain shapes, it would have been an elm, a poplar, a willow, an elder-tree, heather or moss; a little more of certain other shapes and it would have been a sensitive plant, an oyster in a shell, a worm, a fly, a frog, a sparrow, a monkey, a man. When you throw three dice on the table and they all turn up twos; or three, four, five; or two sixes and a one; do you say: 'What a miracle! each die has turned up the same number, when so many other numbers might be turned up; what a miracle! Three dice have turned up three successive numbers; what a miracle! Two sixes and the opposite of the other six has turned up!' I am certain that a man of wit like you would not make these exclamations, for since there are only a certain quantity of numbers on the dice, it is impossible but that one of them should turn up. You are surprised that this matter, mixed up pell-mell by chance, should have built up a man, since so many things are necessary to the construction of his being. But you do not know that this matter, moving towards the design of a man, has stopped a hundred million times on the way to form sometimes a stone, sometimes lead, sometimes coral, sometimes a flower, sometimes a comet, according to the excess or deficiency of certain shapes necessary or unnecessary to compose a man. It is not marvellous that an infinite quantity of matter changing and moving continually should have met together to make the few animals, vegetables and minerals which we see, any more than it is marvellous for a royal pair to turn up in a hundred throws of the dice; and it is impossible but that something should be made from this movement. This thing will always be wondered at by a scatterbrain who will not comprehend how nearly it was not made at all. When the large river
turns a mill, moves the works of a clock, and the little rivulet
does nothing but run and sometimes overflow, you will not say the river has intelligence, because you know it has met with things so placed as to cause all these masterpieces. If a mill had not been placed in its path, it would not have ground the corn; if it had not met the clock it would not have marked the hours; and if the rivulet I spoke of had met the same things it would have performed the same miracles. It is the same with fire, which moves by itself; for when it found organs proper for the agitation necessary to reason, it reasoned; when it found those proper to feel only, it felt; when it found those proper to vegetation, it vegetated. And to prove this, tear out the eyes of a man who is enabled to see by this fire or this soul, and he will cease to see, just as our river will not mark the hours if the clock is destroyed.
"In fine, these first and indivisible atoms make a circle upon which the most embarrassing difficulties of physics roll without difficulty. Even the operation of the senses, which nobody yet has been able to understand, I explain very easily with these little bodies. Let us begin with sight, which, as the most incomprehensible, deserves our first attention. As I suppose, the coverings of the eye, whose openings are like those of glass, transmit the fire-dust we call visual rays, which is stopped by some opaque matter making it rebound; for this fire-dust meets on the way the image of the object which repulses it and, as this image is simply an infinite number of little bodies continually thrown off in equal superficies from the subject looked at, the image thrusts back the rays to our eyes.
"You will not fail to object to me that glass is an opaque and closely-packed body; yet instead of throwing back these other little bodies it allows them to pierce it. But I reply that the pores of glass are made in the same shape as these atoms of fire which pass through it; and just as a wheat-sieve is not fit to sift oats, nor an oat-sieve to sift wheat, so a deal box thin enough to transmit sound is not penetrable by sight and a piece of transparent crystal which allows itself to be pierced by sight is not penetrable by hearing."
I could not prevent myself from interrupting: "But how do you explain by these principles, sir, the fact that we are reflected in a mirror?"
"It is very easy", he replied, "you must suppose that the rays of our eyes pass through the glass and meet behind it a non-diaphanous body which casts them off; they return the way they came and they find spread out upon the mirror the little bodies that move in equal superficies from our own and carry them back to our eyes. Our imagination, which is hotter than the other faculties of the soul, attracts the most subtle of them, with which it makes a reduced portrait.
"The operation of hearing is no more difficult to understand. To be more succinct, let us consider it only in harmony. Suppose then a lute touched by the hands of a master of the art. You will ask me how it happens that I perceive a thing I do not see, so far from me? Do sponges go out of my ears to suck up this music and bring it to me? Or does this lute player beget in my head another little player with another little lute, who has been ordered to sing me the same airs? No. This miracle is caused by the vibrating chord striking the little bodies which compose the air and so driving them into my brain and gently piercing it with these little corporeal nothings. When the string is stretched, the sound is high, because it drives the atoms more vigorously; and the organ so penetrated gives the fantasy sufficient of them to make its picture. If there is not enough, our memory does not complete its image and we are forced to repeat the same sound to it, so that for example it may take from the materials given it by the strains of a saraband enough to complete the portrait of that saraband. But this operation is almost nothing. The wonderful thing is that by this means we are moved sometimes to joy, sometimes to rage, sometimes to pity, sometimes to reflection, sometimes to pain. This happens, I imagine, when the movement received by these little bodies meets within us other little bodies moving in the same way or, on account of their shape, capable of the same motion. The new-comers excite their hosts to move with them and so, when a violent tune meets the fire of our blood (which is disposed to the same movement) it incites this fire to thrust its way out. This is what we call the ardour of courage. If a sound is gentler and has only strength enough to raise a slighter, more wavering flame (because the matter is more volatile), it moves along the nerves, membranes and channels of our flesh and excites the tickling we call joy. The ebullition of the other passions happens in the same way according to whether the little bodies are thrown against us more or less violently, whether they receive movement by meeting other vibrations, and according to what they find to move within us.