REMARKS. We have called this a test of ingenuity. The subject who is given the problem finds himself involved in a difficulty from which he must extricate himself. Means must be found to overcome an obstacle. This requires practical judgement and a certain amount of inventive ingenuity. Various possibilities must be explored and either accepted for trial or rejected. If the amount of invention called for seems to the reader inconsiderable, let it be remembered that the important inventions of history have not as a rule had a Minerva birth, but instead have developed by successive stages, each involving but a small step in advance. It is unnecessary to emphasize at length the function of invention in the higher thought processes. In one form or another it is present in all intellectual activity; in the creation and use of language, in art, in social adjustments, in religion, and in philosophy, as truly as in the domains of science and practical affairs. Certainly this is true if we accept Mason's broad definition of invention as including "every change in human activity made designedly and systematically."[78] From the psychological point of view, perhaps, Mason is justified in looking upon the great inventor as "an epitome of the genius of the world." To develop a Krag-Joergensen from a bow and arrow, a "velvet-tipped" lucifer match from the primitive fire-stick, or a modern piano from the first crude, stringed, musical instrument has involved much the same intellectual processes as have been operative in transforming fetishism and magic into religion and philosophy, or scattered fragments of knowledge into science. [78] Otis T. Mason: _The Origins of Inventions_. (London, 1902.) Psychologically, invention depends upon the constructive imagination; that is, upon the ability to abstract from what is immediately present to the senses and to picture new situations with their possibilities and consequences. Images are united in order to form new combinations. As we have several times emphasized, the decisive intellectual differences among human beings are not greatly dependent upon mere sense discrimination or native retentiveness. Far more important than the raw mass of sense data is the correct shooting together of the sense elements in memory and imagination. This is but another name for invention. It is the synthetic, or apperceptive, activity of the mind that gives the "seven-league boots" to genius. It is, however, a kind of ability which is possessed by all minds to a greater or less degree. Any test has its value which gives a clue, as this test does, to the subject's ability in this direction.