It is obvious that the more there are of such paths as M--N in the brain, and the more of such possible cues or occasions for the recall of _n_ in the mind, the prompter and surer, on the whole, the memory of _n_ will be, the more frequently one will be reminded of it, the more avenues of approach to it one will possess. In mental terms, _the more other facts a fact is associated with in the mind, the better possession of it our memory retains_. Each of its associates becomes a hook to which it hangs, a means to fish it up by when sunk beneath the surface. Together, they form a network of attachments by which it is woven into the entire tissue of our thought. The 'secret of a good memory' is thus the secret of forming diverse and multiple associations with every fact we care to retain. But this forming of associations with a fact, what is it but _thinking about_ the fact as much as possible? Briefly, then, of two men with the same outward experiences and the same amount of mere native tenacity, _the one who_ THINKS _over his experiences most, and weaves them into systematic relations with each other, will be the one with the best memory_. We see examples of this on every hand. Most men have a good memory for facts connected with their own pursuits. The college athlete who remains a dunce at his books will astonish you by his knowledge of men's 'records' in various feats and games, and will be a walking dictionary of sporting statistics. The reason is that he is constantly going over these things in his mind, and comparing and making series of them. They form for him not so many odd facts, but a concept-system--so they stick. So the merchant remembers prices, the politician other politicians' speeches and votes, with a copiousness which amazes outsiders, but which the amount of thinking they bestow on these subjects easily explains. The great memory for facts which a Darwin and a Spencer reveal in their books is not incompatible with the possession on their part of a brain with only a middling degree of physiological retentiveness. Let a man early in life set himself the task of verifying such a theory as that of evolution, and facts will soon cluster and cling to him like grapes to their stem. Their relations to the theory will hold them fast; and the more of these the mind is able to discern, the greater the erudition will become. Meanwhile the theorist may have little, if any, desultory memory. Unutilizable facts may be unnoted by him and forgotten as soon as heard. An ignorance almost as encyclopædic as his erudition may coexist with the latter, and hide, as it were, in the interstices of its web. Those who have had much to do with scholars and _savants_ will readily think of examples of the class of mind I mean.