same point P consciousness perceives light. We propose to show, in the course of this study, that both are right; and that there is no essential difference between the light and the movements, provided we restore to movement the unity, indivisibility, and qualitative heterogeneity denied to it by abstract mechanics; provided also that we see in sensible qualities contractions effected by our memory. Science and consciousness would then coincide in the instantaneous. For the moment all we need say, without examining too closely into the meaning of the words, is that the point P sends to the retina vibrations of light. What happens then? If the visual image of the point P were not already given, we should indeed have to seek the manner in which it had been engendered, and should soon be confronted by an insoluble problem. But, whatever we do, we cannot avoid assuming it to begin with: the sole question is, then, to know how and why this image is chosen to form part of my perception, while an infinite number of other images remain excluded from it. Now I see that the vibrations transmitted from the point P to the various parts of the retina are conducted to the sub-cortical and cortical optic centres, often to other centres as well, and that these centres sometimes transmit them to motor mechanisms, sometimes provisionally arrest them. The nervous elements concerned are, therefore, what give efficacy to the disturbance
