In conducting reviews a pedagogical blunder is apt to be made--a blunder that brings on the evils specified in a former paragraph (105); review is confounded with examination. The two are radically different. If the teacher could be sure of both perfect attention and full comprehension, he himself would go over the ground covered by his first talk once more for the purpose of assisting the memory; the pupils would not be called upon to take part. In this case, we should have neither analytic instruction nor anything resembling an examination. As a matter of fact, however, pupils are usually asked to reproduce what and as much as they remember. This is easily taken to mean that they should have retained everything, which, strictly speaking, is not expected even in an examination. The purpose of an examination is to ascertain the actual state of knowledge, whatever it may prove to be; reviews are conducted for the purpose of increasing and deepening knowledge. If an examination is followed by praise or censure, well and good; a review has nothing to do with either. Since reviewing and drilling, which resembles the former, claim the larger portion of the time devoted to school work, it will be worth while to examine the subject somewhat more closely. 118. Repetition of several ideas intensifies those ideas. It does more than that. If they are of opposed nature, the reciprocal arrest that ensues resists their fusion less during the reproduction than it did in the original act of apprehension. The fusion increases in completeness, and, besides, becomes more uniform, _i.e._, the weaker ideas hold their own better alongside of the stronger. Again, if a series of successive ideas is repeated, the first members of the series of themselves tend to reproduce those that follow before the latter are repeated--a tendency gathering energy in proportion to the frequency of repetition. This fact underlies the increase in rapidity which comes with growing skill. Extraneous thoughts, however, very easily interrupt the psychical process of reproduction.