with matter. When a philosopher seeks to represent to himself the properties of a material object,—of a brain, for example—in order to contrast them with the properties of a psychical activity, it is the properties of sensation that he describes as material; and, in fact, it is by sensation, and sensation alone, that we know these properties. Sensation is so little distinct from them that it is an error to consider it as a means, a process, an instrument for the knowledge of matter. All that we know of matter is not known in or by sensation, but constitutes sensation itself; it is not by the aid of sensation that we know colour; colour is a sensation, and the same may be said of form, resistance, and the whole series of the properties of matter. They are only our sensations clothed with external bodies. It is therefore absolutely legitimate to consider a part of our sensations, the object part, as being of physical nature. This is the opinion to which I adhere.
We come to the second opinion we have formulated. It is, in appearance at least, very different from the first. Its supporters agree that the entire sensation, taken en bloc and unanalysed, is to be termed a psychological phenomenon. In this case, the act of consciousness, included in the sensation, continues to represent a psychical element. They suppose, besides, that the object on which this act operates is psychical;
