There is nothing whatever of this kind about the true and unlearnt memory of events in our history, the memory which represents them. But just because the habit-memory is more immediately and constantly useful to us we notice it more. Indeed we frame on it our familiar conception of what memory really is, and come to regard the true memory of spontaneously arising recollections as only a bad example of the other. 'We ignore the fundamental difference,' so we are told, 'between that which has to be built up by repetition and that which is essentially incapable of being repeated.' No doubt the two intermingle in every-day life and are therefore the more easily confused, not only by our every-day and usually careless selves but even by some careful thinkers. The confusion is dangerous for the thinker and the thinker in consequence becomes dangerous for us. Out of it has come in great part the unreasonable belief that a material brain is the storehouse of immaterial recollections, and that these after becoming either material or, in the physical sense, 'energetic' (as they must be to be stored in a material or 'energetic' way), in some altogether miraculous fashion at times take on consciousness and, as once more immaterial recollections, carry us into our own past. To say that motor-habits, with which when they are established consciousness may have little to do, can be registered in a flexible motor instrument and _acted_ over and over again, is reasonable enough; but that conscious recollections can thus be registered is not only a gratuitous assumption unsupported by the facts of matter or energy or life, but is strictly incredible by any man who really knows and faces those facts. It is better to know and face them with the philosopher, and confess the reality of a spiritual life in which history endures, as well as the reality of a living instrument in which habits are established. No doubt an effort is required if we are to distinguish between the spontaneous and the habitual memories, between the memory of spirit and the habit-memory of its living instrument, the brain and body which together with the spirit are the man; but the effort is well worth making. It gives us a key to unlock many close-shut doors. When we try to learn something (as we are now about to do) concerning the problem of the transmission, through the succession of germ-cells, of the characters that mark out men—the problem of heredity—we find a conspicuous and very interesting use for it. But it has many uses besides that. We can use it with advantage in dealing with all the problems concerning the relations of spirit with matter.