the real action of surrounding images--the other in which all change for
a single image and in the varying measure that they reflect the eventual
action of this privileged image?"[Footnote: Matter and Memory, p. 13
(Fr. p. 11).] We may style one the system of science, the other the
system of consciousness. Now, Realism and Idealism are both incapable of
explaining why there are two such systems at all. Subjective Idealism
derives the system of science from that of consciousness, while
materialistic Realism derives the system of consciousness from that of
science. They have, however, this common meeting-place, that they both
regard Perception as speculative in character--for each of them "to
perceive" is to "know." Now this is just the 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