postulate which Bergson disputes.  The office of perception, according to him, is to give us, not knowledge, but the conditions necessary for action.[Footnote:  Notre croyance a la loi de causalite (Revue de metaphysique et de morale, 1900), p. 658.] A little examination shows us that distance stands for the degree in which other bodies are protected, as it were, against the action of my body against them, and equally too for the degree in which my body is protected from them.[Footnote:  Le Souvenir du present et la fausse reconnaissance in L’Energie spirituelle, pp. 117-161 (Mind-Energy), or Revue philosophique, 1908, pp. 561-593.] Perception is utilitarian in character and has reference to bodily action, and we detach from all the images coming to us those which interest us practically.

Bergson then examines the physiological aspects of the perceptual process.  Beginning with reflex actions and the development of the nervous system, he goes on to discuss the functions of the spinal cord and the brain.  He finds in regard to these last two that “there is only a difference of degree—­there can be no difference in kind—­between what is called the perceptive faculty of the brain and the reflex functions of the spinal cord.  The cord transforms into movements the stimulation received, the brain prolongs into reactions which are merely nascent, but in the one case as in the other, the function of the nerve substance is to conduct, to co-ordinate, or to inhibit movements.[Footnote:  Matter and Memory, pp. 10-11 (Fr. p. 9).] As we rise in the organic series we find a division of physiological labour.  Nerve cells appear, are diversified and tend to group themselves into a system; at the same time the animal reacts by more varied movements to external stimulation.  But even when the stimulation received is not at once prolonged into movement, it appears merely to await its occasion; and the same impression which makes the organism aware of changes in the environment, determines it or prepares it to adapt itself to them.  No doubt there is in the higher vertebrates a radical distinction between pure automatism, of which the seat is mainly in the spinal cord, and voluntary activity which requires the intervention of the brain.  It might be imagined that the impression received, instead of expanding into more movements spiritualizes itself into consciousness.  But as soon as we compare the structure of the spinal cord with that of the brain, we are bound to infer that there is merely a difference of complication, and not a difference in kind, between the functions of the brain and the reflex activity of the medullary system."[Footnote:  Matter and Memory, pp. 17- 18 (Fr. p. 15).] The brain is no more than a kind of central telephone exchange, its office is to allow communication or to delay it.  It adds nothing to what it receives, it is simply a centre where perceptions get into touch with motor mechanisms.  Sometimes the function of the brain