=Note.=--The apperceiving attention is of so great importance in instruction that a word or two more will be in place. The highest stage of this kind of attention is indicated by the words--gaze, scrutinize, listen, handle. The idea of the examined object is already present in consciousness, as is likewise the idea of the class of sense-perceptions looked for. The psychic result turns on the ensuing sense-impressions, on their contrasts, combinations, and reproductions. These are able to induce the corresponding mental states unhindered, because disturbing foreign elements have already been removed and remain excluded. Passing from this highest grade to lower degrees of attention, we find that the idea of the object is not yet--at least not prominently--present, that this itself first needs to be reproduced and made more vivid. The question arises whether this can be accomplished directly or only indirectly. In the former case the idea must be in itself strong enough; in the second it must be sufficiently united with other ideas which it is possible to arouse directly. Moreover, the obstacles to reproduction must be such that they can be overcome. When the apperceiving attention is once under way, it should be utilized and not disturbed. The teaching must take the promised direction until it has satisfied expectation. The solutions must correspond clearly to the problems. Everything must be connected. The attention is disturbed by untimely pauses and the presence of extraneous matter. It is also disturbed by apperceptions that bring into light that which should remain in shadow. This is true of words and phrases too often repeated, of mannerisms of speech--of everything that gives prominence to the language at the expense of the subject-matter, even rhymes, verse-forms, and rhetorical adornment when used in the wrong place. But that which is too simple must be avoided also. In this case the apperception is soon completed; it does not give enough to do. The fullest unit possible is to be sought. A rule of vital importance is that, before setting his pupils at work, the teacher should take them into the field of ideas wherein their work is to be done. He can accomplish this at the beginning of a recitation hour by means of a brief outline view of the ground to be covered in the lesson or lecture. 78. Instruction is to supplement that which has been gained already by experience and by intercourse with others (36); these foundations must exist when instruction begins. If they are wanting, they must be firmly established first. Any deficiency here means a loss to instruction, because the pupils lack the thoughts which they need in order to interpret the words of the teacher.