3. Education as Training of Faculties. A theory which has had great vogue and which came into existence before the notion of growth had much influence is known as the theory of "formal discipline." It has in view a correct ideal; one outcome of education should be the creation of specific powers of accomplishment. A trained person is one who can do the chief things which it is important for him to do better than he could without training: "better" signifying greater ease, efficiency, economy, promptness, etc. That this is an outcome of education was indicated in what was said about habits as the product of educative development. But the theory in question takes, as it were, a short cut; it regards some powers (to be presently named) as the direct and conscious aims of instruction, and not simply as the results of growth. There is a definite number of powers to be trained, as one might enumerate the kinds of strokes which a golfer has to master. Consequently education should get directly at the business of training them. But this implies that they are already there in some untrained form; otherwise their creation would have to be an indirect product of other activities and agencies. Being there already in some crude form, all that remains is to exercise them in constant and graded repetitions, and they will inevitably be refined and perfected. In the phrase "formal discipline" as applied to this conception, "discipline" refers both to the outcome of trained power and to the method of training through repeated exercise. The forms of powers in question are such things as the faculties of perceiving, retaining, recalling, associating, attending, willing, feeling, imagining, thinking, etc., which are then shaped by exercise upon material presented. In its classic form, this theory was expressed by Locke. On the one hand, the outer world presents the material or content of knowledge through passively received sensations. On the other hand, the mind has certain ready powers, attention, observation, retention, comparison, abstraction, compounding, etc. Knowledge results if the mind discriminates and combines things as they are united and divided in nature itself. But the important thing for education is the exercise or practice of the faculties of the mind till they become thoroughly established habitudes. The analogy constantly employed is that of a billiard player or gymnast, who by repeated use of certain muscles in a uniform way at last secures automatic skill. Even the faculty of thinking was to be formed into a trained habit by repeated exercises in making and combining simple distinctions, for which, Locke thought, mathematics affords unrivaled opportunity.