No child under the age of fifteen should receive instruction in subjects which may possibly be the vehicle of serious error, such as philosophy, religion, or any other branch of knowledge where it is necessary to take large views; because wrong notions imbibed early can seldom be rooted out, and of all the intellectual faculties, judgment is the last to arrive at maturity. The child should give its attention either to subjects where no error is possible at all, such as mathematics, or to those in which there is no particular danger in making a mistake, such as languages, natural science, history and so on. And in general, the branches of knowledge which are to be studied at any period of life should be such as the mind is equal to at that period and can perfectly understand. Childhood and youth form the time for collecting materials, for getting a special and thorough knowledge of the individual and particular things. In those years it is too early to form views on a large scale; and ultimate explanations must be put off to a later date. The faculty of judgment, which cannot come into play without mature experience, should be left to itself; and care should be taken not to anticipate its action by inculcating prejudice, which will paralyze it for ever. On the other hand, the memory should be specially taxed in youth, since it is then that it is strongest and most tenacious. But in choosing the things that should be committed to memory the utmost care and forethought must be exercised; as lessons well learnt in youth are never forgotten. This precious soil must therefore be cultivated so as to bear as much fruit as possible. If you think how deeply rooted in your memory are those persons whom you knew in the first twelve years of your life, how indelible the impression made upon you by the events of those years, how clear your recollection of most of the things that happened to you then, most of what was told or taught you, it will seem a natural thing to take the susceptibility and tenacity of the mind at that period as the ground-work of education. This may be done by a strict observance of method, and a systematic regulation of the impressions which the mind is to receive.