has already shown that color can not be thought of without space or space without color, the task of determining the concrete object to which the witness attaches the qualities he speaks of, will still be overlooked hundreds of times. It is further of importance that everybody has learned to know the object he speaks about through repetition, that different relations have shown him the matter in different ways. If an object has impressed itself upon us, once pleasurably and once unpleasantly, we can not derive the history and character of the present impression from the object alone, nor can we find it merely in the synthetic memory sensations which are due to the traces of the former coalescing impressions. We are frequently unable, because of this coalescing of earlier impressions, to keep them apart and to study their effect on present impressions. Frequently we do not even at all know why this or that impression is so vivid. But if we are ignorant with regard to what occurs in ourselves, how much can we know about others? Exner calls attention to the fact that it is in this direction especially, that the “dark perceptions” play a great rôle. “A great part of our intelligence depends on the ability of these ‘dark perceptions’ to rise without requiring further attention, into the field of consciousness. There are people, e.g., who recognize birds in their flight without knowing clearly what the characteristic flight for any definite bird may be. Others, still more intelligent, know at what intervals the flyers beat their wings, for they can imitate them with their hands. And when the intelligence is still greater, it makes possible a correct description in words.” Suppose that in some important criminal case several people, of different degrees of education and intelligence, have made observations. We suppose that they all want to tell the truth, and we also suppose that they have observed and apprehended their objects correctly. Their testimonies, nevertheless, will be very different. With the degree of intelligence rises the degree of effect of the “dark subconscious perceptions.” They give more definite presentation and explanation of the testimony; they turn bare assertions into well-ordered perceptions and real representations. But we generally make the mistake of ascribing the variety of evidence to varying views, or to dishonesty.