Finally, in a most important letter, ("Report of the French Philosophical Society", meeting, 26th February 1903.) Mr Bergson becomes a little more precise still. We must certainly not confuse the affirmation of liberty with the negation of physical determinism; "for there is more in this affirmation than in this negation." All the same, liberty supposes a certain contingence. It is "psychological causality itself," which must not be represented after the model of physical causality. In opposition to the latter, it implies that between two moments of a conscious being there is not an equivalence admitting of deduction, that in the transition from one to the other there is a genuine creation. Without doubt the free act is not without explanatory reasons. "But these reasons have determined us only at the moment when they have become determining; that is, at the moment when the act was virtually accomplished, and the creation of which I speak is entirely contained in the progress by which these reasons have become determining." It is true that all this implies a certain independence of mental life in relation to the mechanism of matter; and that is why Mr Bergson was obliged to set himself the problem of the relations between body and mind. We know that the solution of this problem is the principal object of "Matter and Memory". The thesis of psycho-physiological parallelism is there peremptorily refuted. The method which Mr Bergson has followed to do so will be found set out by himself in a communication to the French Philosophical Society, which it is important to study as introduction. ("Report" of meeting, 2nd May 1901.) The paralogism included in the very enunciation of the parallelist thesis is explained in a memoire presented to the Geneva International Philosophical Congress in 1904. ("Revue de Metaphysique et de Morale", November 1904.) But the actual proof is made by the analysis of the memoire which fills chapters ii. and iii. of the work cited above. (An extremely suggestive resume of these theses will be found in the second lecture on "The Perception of Change".) It is there established, by the most positive arguments, (Instead of brutally connecting the two extremes of matter and mind, one regarded in its highest action, the other in its most rudimentary mechanism, thus dooming to certain failure any attempt to explain their actual union, Mr Bergson studies their living contact at the point of intersection marked by the phenomena of perception and memory: he compares the higher point of matter--the brain--and the lower point of mind--certain recollections--and it is between these two neighbouring points that he notes a difference, by a method no longer dialectic but experimental.) that all our past is self-preserved in us, that this preservation only makes one with the musical character of duration, with the indivisible nature of change, but that one part only is conscious of it, the part