If, instead, we stick to the scientific view, we find the following facts. First, we have everywhere with us the fact that the earlier experiences may again enter into consciousness as memory images or as imaginative ideas, that is, in the order in which they are experienced a long time before or in a new order, either with a feeling of acquaintance or without it. Certainly at no time is the millionth part of what we may be able to reproduce present in our consciousness. Where are those words of the language, those faces of our friends, those landscapes, and those thoughts; where have they lingered in the time of their seclusion? Scientific psychology has no right to propose any other theory as explanation but that no mental states at all remain and that all which remained was the disposition of physiological centers. When I coupled the impression of a man with the sound of his name, a certain excitement of my visual centers occurred together with the excitement of my acoustical centers; the connecting paths became paths of least resistance, and any subsequent excitement of the one cell group now flows over into the other. It is the duty of physiology to elaborate such a clumsy scheme and to make us understand in detail how those processes in the neurons can occur and it is not the duty of psychology to develop detailed physiological hypotheses. Psychology has to be satisfied with the fact that all the requirements of the case can be furnished by principle through physiological explanation. Least of all ought we to be discouraged by the mere complexity of the process. If a simple sound and a simple color sensation, or a simple taste and simple smell sensation, can associate themselves through mere nervous conditions of the brain, then there is nothing changed by going over to more and more complex contents of consciousness. We may substitute a whole landscape for a color patch or the memory of a book for a word, but we do not reach by that a point where the physiological principle of explanation, once admitted, begins to lose its value. Complexity is certainly in good harmony with the bewildering manifoldness of those thousands of millions of possible connections between the brain cells.