It was formerly customary to class memory with the various faculties of the mind, but later psychology no longer so considers it. Memory is now regarded as a power of the general mind, manifesting in connection with every faculty of the mind. It is now regarded as belonging to the great subconscious field of mentation, and its explanation must be sought there. It is utterly unexplainable otherwise. The importance of memory cannot be overestimated. Not only does a man's character and education depend chiefly upon it, but his very mental being is bound up with it. If there were no memory, man would never progress mentally beyond the mental state of the newborn babe. He would never be able to profit by experience. He would never be able to form clear perceptions. He would never be able to reason or form judgments. The processes of thought depend for material upon the memory of past experiences; this material lacking, there can be no thought. Memory has two important general functions, viz.: (1) The _retention_ of impressions and experiences; and (2) the _reproduction_ of the impressions and experiences so retained. It was formerly held that the memory retained only a portion of the impressions and experiences originally noted by it. But the present theory is that it retains every impression and experience which is noted by it. It is true that many of these impressions are never reproduced in consciousness, but experiments tend to prove, nevertheless, that the records are still in the memory and that appropriate and sufficiently strong stimuli will bring them into the field of consciousness. The phenomena of somnambulism, dreams, hysteria, delirium, approach of death, etc., show that the subconscious mind has an immense accumulation of apparently forgotten facts, which unusual stimuli will serve to recall. The power of the memory to reproduce the retained impressions and experiences is variously called remembrance, recollection, or memory. This power varies materially in various individuals, but it is an axiom of psychology that the memory of any person may be developed and trained by practice. The ability to recall depends to a great extent upon the clearness and depth of the original impression, which in turn depends upon the degree of attention given to it at the time of its occurrence. Recollection is also greatly aided by the law of association, or the principle whereby one mental fact is linked to another. The more facts to which a given fact is linked, the greater the ease by which it is recalled or remembered. Recollection is also greatly assisted by use and exercise. Like the fingers, the memory cells of the brain become expert and efficient by use and exercise, or stiff and inefficient by lack of the same.