All philosophers agree that consciousness gives us knowledge of psychological phenomena. But is this all it gives us?

We now know that consciousness also allows us to see a being – the self – whose existence we acknowledge constantly and to which all psychological phenomena are related. The pronoun “I” or “me,” expressed or implied, is the subject of all our sentences. When I say, “It's hot,” what I mean is, “I am experiencing a sensation of heat.” “The external world exists” is a way of saying, “I hold that the external world exists.” The self is thus the center around which all our states of consciousness converge, bringing unity to our inner life. But if this much is well established, we still have to determine whether the idea of the self is an invention, a construction of our mind, or given by consciousness itself. Here we come to a question analogous to that dealt with in our discussion of the origin of the idea of externality. So we'll use the same method here that we did there.

Every idea is either given or constructed.

Is the idea of the self constructed? The only materials that might be used to construct it are the various states of consciousness, and the method of construction would consist in extracting from them one or more characteristics that are somehow analogous to the idea of the self. This idea – like that of weight – could then be formed through generalization.