No objection can be made to this assertion as long as we take into account merely the general fact that the percept is determined in part by the organisation of the subject. The matter would be far otherwise if we were in a position to say what part exactly is played by our perceiving in the occurrence of a percept. We should know then what happens to a percept whilst it is being perceived, and we should also be able to determine what character it must possess before it comes to be perceived. This leads us to turn our attention from the object of a perception to the subject of it. I am aware not only of other things but also of myself. The content of my perception of myself consists, in the first instance, in that I am something stable in contrast with the ever coming and going flux of percepts. The awareness of myself accompanies in my consciousness the awareness of all other percepts. When I am absorbed in the perception of a given object I am, for the time being, aware only of this object. Next I become aware also of myself. I am then conscious, not only of the object, but also of my Self as opposed to and observing the object. I do not merely see a tree, I know also that it is I who see it. I know, moreover, that some process takes place in me when I observe a tree. When the tree disappears from my field of vision, an after-effect of this process remains, viz., an image of the tree. This image has become associated with my Self during my perception. My Self has become enriched; to its content a new element has been added. This element I call my idea of the tree. I should never have occasion to talk of ideas, were I not aware of my own Self. Percepts would come and go; I should let them slip by. It is only because I am aware of my Self, and observe that with each perception the content of the Self is changed, that I am compelled to connect the perception of the object with the changes in the content of my Self, and to speak of having an idea.