Association in Memory.
It follows from a consideration of the Law of Association that when one wishes to impress a thing upon the memory he should, as an authority says, "Multiply associations; entangle the fact you wish to remember in a net of as many associations as possible, especially those that are logical." Hence the advice to place your facts in groups and classes in the memory. As Blackie says: "Nothing helps the mind so much as order and classification. Classes are always 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."