The chief possible virtue of tendency conceptions is in introducing some sort of order in complex phenomena. If the observer tries to enumerate all the body movements, all the electronic gyrations, all the nuances of social adjustment which are thinkable in a given constellation of personality events, he is likely to become lost in aimless classification, and to prove barren in the invention of procedures which are calculated to elicit particular aspects of the whole which may be of high predictive value. The human mind is able to operate with a very small number of categories with which to introduce order into events, particularly when these are, for the most part, still defined qualitatively. Clarity of thought demands economy in the orienting frames of thought. How a tendency simplification may lead to fruitful research for predictively valuable particulars is shown in the case of Freud, in contrast to Janet. Janet made remarkably clear classifications of the psychopathological facts as he saw them, and although his terms and categories were abundant, his work was comparatively sterile of novel procedures for the modification of human personalities. Even his classificatory pursuits were hampered by his little-criticized assumptions. His notion that dreams were passing confusions which were traceable to diminished psychological tension in sleep deprived dream material of all significance as classifiable data, and he almost completely ignored it. Freud, who tended to operate with a few bold tendency simplifications, brought into the range of observation whole categories of data which have high predictive value. When tendency simplifications are used until vast numbers of instances accumulate of their supposed operation, “subtendencies” (such as the variations of the manifestations of the Oedipus constellation) multiply apace until the problems of rendering one tendency consistent with the expressions of another one carry scientific speculations into the logical molds of legalism and dogmatic theology. If the subtendencies are not modified, and long lists of special tendencies are added, terminological difficulties likewise arise in applying the unwieldy list. The long inventories of supposed instincts are less at fault because they imply an unwarranted assurance about the innate propensities of man than because they are “too numerous to mention,” and introduce confusion rather than orienting principles in the field of study. Although the prediction of one set of tangible reactions from another is the aim of scientific formulation, this by no means implies, then, that the reactive style of thinking is the one best calculated to guide the attention of the thinker to the selection of the most fruitful hypotheses (“if” predictions). Indeed, especially valuable results have been secured in the personality field by the pattern of thinking which views a cross-section of facts as an expression of a few tendencies.