It has also been noted that all such words as incomprehensible, unconditioned, infinite, unknowable, are in their nature privatives, they are not a thought but are only one element of a thought. As has been shown in the first chapter, every thought is made up of a positive and a privative, and it is absurd and unnatural to separate the one from the other. The concept man, regarded as a division of the higher concept animal, is made up of man and not-man. In so far as other animals are included under the term “not-man” they do not come into intelligent cognition; but that does not mean that they cannot do so. So “the unconditioned” is really a part of the thought of “the conditioned,” the “unknowable” a part of the “knowable,” the “infinite” a part of the thought of the “finite.” Under material images these privatives, as such, cannot be expressed; but in pure thought which deals with symbols and types alone, they can be. But if the abstract laws of thought themselves are confined in the limits of one kind of intelligence, then we cannot take an appeal to them to attack this sophism. Therefore on maintaining their integrity the discussion must finally rest. This has been fully recognized by thinkers, one of whom has not long since earnestly called attention to “the urgent necessity of fathoming the psychical mechanism on which rests all our intellectual life.”[101-1] In this endeavor the attempt has been made to show that the logical laws are derived in accordance with the general theory of evolution from the natural or material laws of thinking. These, as I have previously remarked, are those of the association of ideas, and come under the general heads of contiguity and similarity. Such combinations are independent of the aim of the logical laws, which is _correct_ thinking. A German writer, Dr. Windelband, has therefore argued that as experience, strengthened by hereditary transmission, continued to show that the particular combinations which are in accord with what we call the laws of thought furnished the best, that is, the most useful results, they were adopted in preference to others and finally assumed as the criteria of truth. Of course it follows from this that as these laws are merely the outcome of human experience they can have no validity outside of it. Consequently, adds the writer I have quoted, just as the study of optics teaches us that the human eye yields a very different picture of the external world from that given by the eye of a fly, for instance, and as each of them is equally far from the reality, so the truth which our intelligence enables us to reach is not less remote from that which is the absolutely true. He considers that this is proven by the very nature of the “law of contradiction” itself, which must be inconsistent with the character of absolute thought. For in the latter, positive truth only can exist, therefore no negation, and no law about the relation of affirmative to negative.[102-1]