that has nothing to do with the experienced facts of life, it is found indigenous in experience:--the factor by which past experiences are purified and rendered into tools for discovery and advance. The term "abstract" has a rather bad name in popular speech, being used to signify not only that which is abstruse and hard to understand, but also that which is far away from life. But abstraction is an indispensable trait in reflective direction of activity. Situations do not literally repeat themselves. Habit treats new occurrences as if they were identical with old ones; it suffices, accordingly, when the different or novel element is negligible for present purposes. But when the new element requires especial attention, random reaction is the sole recourse unless abstraction is brought into play. For abstraction deliberately selects from the subject matter of former experiences that which is thought helpful in dealing with the new. It signifies conscious transfer of a meaning embedded in past experience for use in a new one. It is the very artery of intelligence, of the intentional rendering of one experience available for guidance of another. Science carries on this working over of prior subject matter on a large scale. It aims to free an experience from all which is purely personal and strictly immediate; it aims to detach whatever it has in common with the subject matter of other experiences, and which, being common, may be saved for further use. It is, thus, an indispensable factor in social progress. In any experience just as it occurs there is much which, while it may be of precious import to the individual implicated in the experience, is peculiar and unreduplicable. From the standpoint of science, this material is accidental, while the features which are widely shared are essential. Whatever is unique in the situation, since dependent upon the peculiarities of the individual and the coincidence of circumstance, is not available for others; so that unless what is shared is abstracted and fixed by a suitable symbol, practically all the value of the experience may perish in its passing. But abstraction and the use of terms to record what is abstracted put the net value of individual experience at the permanent disposal of mankind. No one can foresee in detail when or how it may be of further use. The man of science in developing his abstractions is like a manufacturer of tools who does not know who will use them nor when. But intellectual tools are indefinitely more flexible in their range of adaptation than other mechanical tools.