Gregory posits not only that review and application are the “essential conditions of all true teaching,” but also that “not to review is to leave the job half done.” The aim of reviewing material is threefold:

Reviewing can include a number of different aspects, as well:

Thus, Gregory notes that it is difficult to overstate the importance, the necessity, of review. In fact, he goes so far as to say, “No time in teaching is spent more profitably than that spent in reviewing.” Our reviewing should not be mere repetition, but should involve fresh conceptions and new associations. There is a spectrum of types of review, from the simple repetition to the complete restudy; each point upon that spectrum holds value and has a place in our efforts. Reviews should be frequent, thorough, and interesting. In fact, going over information after a lapse of time allows the opportunity for a fresh perspective and new connections. Not only that, but it also allows for “mental incubation.” Our brains work without our conscious effort (Gregory says this, but this statement is in fact the thesis of the interesting popular economics book, Blink), so when we come back to a thought after time has passed, we are more prepared to receive it and incorporate it or respond to it properly.

Gregory especially elaborates upon the necessity of a final year-end review. The final review, he says, should never be omitted, should be searching, should be comprehensive, and should demonstrate masterful competency (by teacher and student alike). Often, Gregory says, our teaching is pouring water into broken cisterns. Review will not affect the quality of the water, but it affects the cisterns, patching them up, repairing and preventing leaks.