If this is correct, what really happens when, as common sense would say, we are conscious of a table, is more or less as follows. First there is a physical process external to the body, producing a stimulus to the eye which occurs rarely (not never) in the absence of an actual physical table. Then there is a process in the eye, nerves, and brain, and finally there is a coloured pattern. This coloured pattern, by the law of association, gives rise to tactual and other expectations and images; also, perhaps, to memories and other habits. But everything in this whole series consists of a causally continuous chain of events in space-time, and we have no reason to assert that the events in us are so very different from the events outside us--as to this, we must remain ignorant, since the outside events are only known as to their abstract mathematical characteristics, which do not show whether these events are like “thoughts” or unlike them. It follows that “consciousness” cannot be defined either as a peculiar kind of relation or as an intrinsic character belonging to certain events and not to others. “Mental” events are not essentially relational, and we do not know enough of the intrinsic character of events outside us to say whether it does or does not differ from that of “mental” events. But what makes us call a certain class of events “mental” and distinguish them from other events is the combination of sensitivity with associative reproduction. The more markedly this combination exists, the more “mental” are the events concerned; thus mentality is a matter of degree. There is, however, a further point which must be discussed in this connection, and that is “self-consciousness”, or awareness of our own “mental” events. We already had occasion to touch on this in Chapter XVI in connection with Descartes’ “I think, therefore I am”. But I want to discuss the question afresh in connection with “consciousness”.