Psychology there is found a constant repetition of the injunction to cultivate the faculty of attention and concentration. Halleck says: “Haziness of perception lies at the root of many a bad memory. If perception is definite, the first step has been taken toward insuring a good memory. If the first impression is vivid, its effect upon the brain cells is more lasting. All persons ought to practice their visualizing power. This will react upon perception and make it more definite. Visualizing will also form a brain habit of remembering things pictorially, and hence more exactly.”
The subject of association must also receive its proper share of attention, for it is by means of association that the stored away records of the memory may be recovered or re-collected. As Blackie says: “Nothing helps the mind so much as order and classification. Classes are few, individuals many: to know the class well is to know what is most essential in the character of the individual, and what burdens the memory least to retain.” And as Halleck says regarding the subject of association by relation: “When-
