I am, moreover, in exactly the same position when I adopt the exceptional point of view and think of my own thought-processes. I can never observe my present thought, I can only make my past experiences of thought-processes subsequently the objects of fresh thoughts. If I wanted to watch my present thought, I should have to split myself into two persons, one to think, the other to observe this thinking. But this is impossible. I can only accomplish it in two separate acts. The observed thought-processes are never those in which I am actually engaged but others. Whether, for this purpose, I make observations on my own former thoughts, or follow the thought-processes of another person, or finally, as in the example of the motions of the billiard balls, assume an imaginary thought-process, is immaterial. There are two things which are incompatible with one another: productive activity and the theoretical contemplation of that activity. This is recognised even in the First Book of Moses. It represents God as creating the world in the first six days, and only after its completion is any contemplation of the world possible: "And God saw everything that he had made and, behold, it was very good." The same applies to our thinking. It must be there first, if we would observe it. The reason why it is impossible to observe the thought-process in its actual occurrence at any given moment, is the same as that which makes it possible for us to know it more immediately and more intimately than any other process in the world. Just because it is our own creation do we know the characteristic features of its course, the manner in which the process, in detail, takes place. What in the other spheres of observation we can discover only indirectly, viz., the relevant objective nexus and the relations of the individual objects, that is known to us immediately in the case of thought. I do not know off-hand why, for perception, thunder follows lightning, but I know immediately, from the content of the two concepts, why my thought connects the concept of thunder with that of lightning. It does not matter for my argument whether my concepts of thunder and lightning are correct. The connection between the concepts I have is clear to me, and that through the very concepts themselves.