Memory is of two sorts, conscious and unconscious. The conscious memory contains experiences which can be recollected, such as the words of a language or the sights we have seen. The unconscious memory contains impressions which cannot be recalled to mind, but which are none the less important. Thus, we learn to use our limbs, a process which involves a precise but quite unconscious adjustment of the actions of numerous nerves and muscles, the very names and existences of which are known only to the anatomist. So, also, in youth we unconsciously imitate our fellows, adopting in great measure their mental tones and attitudes without knowing how or when we were influenced. Much, too, that was once capable of being recalled is added to that hidden store, and, though apparently lost, remains potent for good or evil. Our minds are like floating icebergs, of which the visible part is but a fraction of the whole, and are moved by deep currents in a seemingly unaccountable way. At birth the mind of a child, unlike that of a beetle, is practically blank. Sights and sounds and the other feelings convey no meanings to it. But soon the messages sent by the sensation are understood. In a few weeks the child evolves order out of chaos, and comprehends to a wonderful degree the world around it. It learns to move its muscles in a purposeful way, and in a year or two is able to walk and speak a language, and do a vast deal more besides. In these early years, the period of man’s greatest mental activity, are made his most valuable and indispensable acquirements. But as he becomes more and more completely equipped for the battle of life, his powers of adding to the store slowly decline. In adult life the gains are balanced by the losses. In old age the losses exceed the gains. Compare the perfection with which the young acquire the manners of society, and every accent, inflection, and intonation of a language, with the imperfections displayed when learning is undertaken later. [Sidenote: Habits are Imitation Instincts]