M. Bergson has thought to overcome it by attacking it in the following way. He has the very ingenious idea of changing the position of the representation in relation to the cerebral movement. The materialist places the representation after this movement and derives it from the movement; the parallelist places it by the side of the movement and in equivalence to it. M. Bergson places it before the movement, and supposes it to play with regard to it the part of exciting cause, or simply that of initiator. This cerebral movement becomes an effect of the representation and a motor effect. Consequently the nervous system passes into the state of motor organ: the sensory nerves are not, as supposed, true sensory nerves, but they are the commencements of motor nerves, the aim of which is to lead the motor excitements to the centres which play the part of commutators and direct the current, sometimes by one set of nerves, sometimes by others. The nervous system is like a tool held in the hand: it is a vehicle for action, we are told, and not a substratum for cognition. I cannot here say with what ingenuity, with what powerful logic, and with what close continuity of ideas M. Bergson develops his system, nor with what address he braves its difficulties. His mind is remarkable alike for its power of systematisation and its suppleness of adaptation. Before commencing to criticise him, I am anxious to say how much I admire him, how much I agree with him throughout the critical part of his work, and how much I owe to the perusal of his book, _Matiere et Memoire_. Though I was led into metaphysics by private needs, though some of the ideas I have set forth above were conceptions of my own (for example, the criticism of the mechanical theory of matter, and the definition of sensation), before I had read M. Bergson's book, it cannot be denied that its perusal has so strongly modified my ideas that a great part of these are due to him without my feeling capable of exactly discerning which; for ideas have a much more impersonal character than observations and experiments. It would therefore have been ungrateful to criticise him before having rendered him this tribute.