Aside from reading, the elements involved in keeping a commonplace book are marking passages, recording them, and then reviewing and thinking about them from time to time. The one additional element that is almost always ignored is annotating. To be sure there is never enough time to thoughtfully annotate passages, even the most provocative of them. I am as guilty of that as anyone and yet I feel that the real benefit of the commonplace experience comes during the process of annotating. It is there that you really confront the meaning of the passage, why it was selected, and its implications for your beliefs and actions. It also consolidates the memory process so that the passages can be called up in other situations where they are
As William Coe put it in an article on commonplace books in the New York Times: The key word for the commonplace book is "annotated." It is not just an anthology; the compiler reacts to the passages he has chosen or tells what the passages have led him to think about. A piece of prose, a poem, an aphorism can trigger the mind to consider a parallel, to dredge something from the memory, or perhaps to speculate with further range and depth on the same theme.