The senses should, then, correspond to external realities. They have been created, not by the perceiving being, but by the perceptible environment. It is the light that has created the eye, just as, in our houses, it has created the windows. Where there is no light, fish become blind. This is perhaps the direct proof, for if light is the creation of the eye, this creation can occur at the bottom of the sea quite as well as on the surface of the earth. Another proof: these same fish, having become blind, but still requiring a luminous habitat, create for themselves in the night of the abysses, not eyes, but apparatus directly productive of light; and this artificial light creates anew the atrophied eye. The senses are then clearly the product of the environment. That is all they can do, moreover, their utility being nil, if the environment is not perceptible. It might still be objected that it is the nervous system which, having intuition of an environment to be perceived, creates for itself organs adapted to this perception. But this is merely begging the question; for, either the nervous system has knowledge of the external environment, which means that it already has senses, or else it has no senses, and thus can have no knowledge. A more serious objection would be that, sensorial aptitude being a property of the nervous system, it would afterwards create for itself organs in order to perceive more distinctly, and clearly differentiated, the various natural phenomena. This view would explain up to a certain point the creation of sensorial organs, but not the existence of the senses themselves as sensitive power. It is, moreover, certain that the nervous system acts rather by tyrannizing the organs at its disposal, than by seeking to modify these organs or to create new ones. It is a power which evidently exceeds the limits of its capacity. It has, on the contrary, devolved upon the external phenomena which, in acting mechanically on the living matter, produce in it local modifications. The organs of the senses seem to be nothing other than surfaces sensitized by the very agents which, once their work is done, will reflect in them their particular physiognomy. The eye--let us take once more this example, and repeat it--is a creation of light. Since they are themselves the work of the principal general phenomena, the senses ought then to agree exactly--allowing for approximation--with the very nature which has created them. The luminous environment is not, in this case, a dream, but a reality, and a reality existing prior to the eye which perceives it; and, since the eye is the very product of light, objects situated in this luminous environment should be perceived by it as an exact image, just as the drill which creates a hole, creates it strictly to its size, its form, its image. Bacon said that the senses are holes. Here this is only a metaphor. IV