By starting with the consideration of matter as something already existent, and mind as something which has yet to come into existence, nineteenth-century science arrived at this impassable gap in its explanation of human world-experience. It is still impassable and will remain so forever because the premise with which science started is wholly wrong. If a human being takes a wrong road and cannot arrive at his destination, the sensible course is for him to retrace his steps and take the right road. There is no other course open to science if it wants to arrive at a satisfactory explanation. It must go back from the materialistic line of thought and start with the mentalistic one, that is, with mind first. The essential point which must not be missed is that unless consciousness existed previously, the sense stimuli might strike on the brain forever but they would never get any response. There is no hope for success in solving this problem along the materialistically scientific road of explanation so long as it pursues a rigidly non-metaphysical course, no hope that the secret of consciousness dwells in a stimulated nerve or that the medium of interaction between thought and flesh is in colloidal structure. That secret dwells where it always has dwelt--in the mind alone--and both nerve and colloidal structure dwell there too. Once he grasps this fact, that the whole of his life-experience is only a play of attention, he will have grasped the essence of mentalism. This will liberate him intellectually from materialism.
-- Notebooks Category 21: Mentalism > Chapter 1 : The Sensed World > # 137
