learner is not, therefore, it cannot be, identical with the formulated, the crystallized, and systematized subject matter of the adult; the material as found in books and in works of art, etc. The latter represents the possibilities of the former; not its existing state. It enters directly into the activities of the expert and the educator, not into that of the beginner, the learner. Failure to bear in mind the difference in subject matter from the respective standpoints of teacher and student is responsible for most of the mistakes made in the use of texts and other expressions of preëxistent knowledge.
The need for a knowledge of the constitution and functions, in the concrete, of human nature is great just because the teacher's attitude to subject matter is so different from that of the pupil. The teacher presents in actuality what the pupil represents only in posse. That is, the teacher already knows the things which the student is only learning. Hence the problem of the two is radically unlike. When engaged in the direct act of teaching, the instructor needs to have subject matter at his fingers' ends; his attention should be upon the attitude and response of the pupil. To understand the latter in its interplay with subject matter is his task, while the pupil's mind, naturally, should be not on itself but on the topic in hand. Or to state the same point in a somewhat different manner: the teacher should be occupied not with subject matter in itself but in its interaction with the pupil's present needs and capacities. Hence simple scholarship is not enough. In fact, there are certain features of scholarship or mastered subject matter—taken by itself—which get in the way of effective teaching unless the instructor's habitual attitude is one of concern with its interplay in the pupil's own experience. In the first place, his knowledge extends indefinitely beyond the range of the pupil's acquaintance. It involves principles which are beyond the immature pupil's understanding and interest. In and of itself, it may no more represent the living world of the pupil's experience than the astronomer's
