Advance in insight and control came only when the mind turned squarely around. After it had dawned upon inquirers that their alleged causal forces were only names which condensed into a duplicate form a variety of complex occurrences, they set about breaking up phenomena into minute detail and searching for correlations, that is, for elements in other gross phenomena which also varied. Correspondence of variations of elements took the place of large and imposing forces. The psychology of behavior is only beginning to undergo similar treatment. It is probable that the vogue of sensation-psychology was due to the fact that it seemed to promise a similar detailed treatment of personal phenomena. But as yet we tend to regard sex, hunger, fear, and even much more complex active interests as if they were lump forces, like the combustion or gravity of old-fashioned physical science. It is not hard to see how the notion of a single and separate tendency grew up in the case of simpler acts like hunger and sex. The paths of motor outlet or discharge are comparatively few and are fairly well defined. Specific bodily organs are conspicuously involved. Hence there is suggested the notion of a correspondingly separate psychic force or impulse. There are two fallacies in this assumption. The first consists in ignoring the fact that no activity (even one that is limited by routine habit) is confined to the channel which is most flagrantly involved in its execution. The whole organism is concerned in every act to some extent and in some fashion, internal organs as well as muscular, those of circulation, secretion, etc. Since the total state of the organism is never exactly twice alike, in so far the phenomena of hunger and sex are never twice the same in fact. The difference may be negligible for some purposes, and yet give the key for the purposes of a psychological analysis which shall terminate in a correct judgment of value. Even physiologically the context of organic changes accompanying an act of hunger or sex makes the difference between a normal and a morbid phenomenon.