Bergson does not accept the hypothesis of psycho-physical parallelism. In the first of his four lectures on La Nature de l'Ame, given at London University in 1911, we find him criticizing the notion that consciousness has no independence of its own, that it merely expresses certain states of the brain, that the content of a fact of consciousness is to be found wholly in the corresponding cerebral state. It is true that we should not find many physiologists or philosophers who would tell us now that "the brain secretes thought as the liver secretes bile." [Footnote: Cabanis (1757-1808). Rapports du physique et du morale de l'homme, 1802. See quotation by William James in Human Immortality. Note (4) in his Appendix.] But there was an idea that, if we could see through the skull and observe what takes place in the brain, if we had an enormously powerful microscope which would permit us to follow the movements of the molecules, atoms, electrons, of the brain, and if we had the key to the correspondence between these phenomena and the mind, we should know all the thoughts and wishes of the person to whom the brain belonged--we should see what took place in his soul, as a telegraph operator could read by the oscillation of his needles the meaning of a message which was sent through his instrument. The notion of an equality or parallelism between conscious activity and cerebral activity, was commonly adopted by modern physiology, and it was adopted without discussion as a scientific notion by the majority of philosophers. Yet the experimental basis of this theory is extremely slight, indeed altogether insufficient, and in reality the theory is a metaphysical conception, resulting from the views of the seventeenth century thinkers who had hopes of "a universal mathematic." The idea had been accepted that all was capable of determination in the psychical as well as the physical world, inasmuch as the psychical was only a reflex of the physical. Parallelism was adopted by science because of its convenience.[Footnote: See The Times of Oct. 21, 1911.] Bergson, however, pointed out that philosophy ought not to accept it without criticism, and maintained, moreover, that it could not stand the criticism that might be brought against it. Relation of soul and body was undeniable, but that it was a parallel or equivalent relation he denied most emphatically. That criticism he had launched himself with great vigour in 1901 at a Meeting of the Societe francaise de philosophie,[Footnote: See Bibliography, p. 153.] and on a more memorable occasion, at the International Congress of Philosophy at Geneva in 1904.[Footnote: See Bibliography, p. 154.] Before the Philosophical Society he lectured on Le Parallelisme psycho-physique et la Metaphysique positive, and propounded the following propositions: