In the adult, as well as in the young and the infant, the culture of the mind is carried on in every case by the operation of the same principle.--However various the means employed for this purpose may be, they all depend for their success upon this kind of active thought,--this reiteration of the _ideas_ suggested in the course of reading, hearing, observation, or reasoning. A man may turn a wheel, or point pins, or repeat words from infancy to old age, without his mind's being in the least perceptible degree benefited by such operations; while the mill-wright, the engineer, or the artist, whose employments require varied and active thought, cannot pursue his employment for a single day, without mental culture, and an acquisition of mental strength.--The reason is, that in mere mechanical operations there is nothing to induce this act of reiteration,--this active mental exercise of which we are speaking. In the former case, the individual is left to the train of thought in the mind, which appears to afford no mental cultivation;--whereas, in the latter, the mind is, by the acts of comparing, judging, trying, and deciding, which the nature of his occupation renders necessary, constantly excited to active thought,--that is, to the reiteration of the several ideas presented to it. These remarks may be thought by some to be exceedingly commonplace and self-evident.--It may be so. If they be admitted, we ask no more.--Our purpose at present is answered, if we have detected a principle in education, by the operation of which the powers of the mind are invariably expanded and strengthened;--an effect which, so far as we yet know, in its absence never takes place. It is by means of this principle alone that Nature accomplishes this important object, both in young and old; but its effects are especially observable in the young, where, her operations not being so much interfered with, we find her producing by its means the most extraordinary effects, and that even during the most imbecile period of her pupil's existence.