Of the correctness of these facts, every one may be convinced, by recollecting what must often have taken place with himself. When at any time the mind is exhausted while reading, we continue to read on, page after page, and when we have finished, we find, that not a single truth has made its way to the memory. Now this did not arise from any difficulty in comprehending the ideas in the book, because it does not make much difference whether the subject has been simple or otherwise; neither did it arise from the want of all mental activity, for the mind was so much engaged as to read every word and every letter in the pages upon which we were occupied. But it arose entirely from the want of that principle of which we are here speaking. The words were read mechanically, and the ideas were either not thought of, or at least they were not reiterated by the mind, and therefore it is that they are lost,--and no effort can ever again recall them. The proof of the accuracy of these views will still be found in the circumstance, that if, while the person is reading, this act of the reiteration of some one or more of the ideas be in any way forced upon him, _these_ ideas thus reiterated will afterwards be remembered, although all the others are lost. Here then we have arrived at a principle connected with the acquisition of knowledge, by attending to which education may be made most efficient for that purpose; but without which, education must remain a mere mechanical routine of barren exercises. No idea, no truth, we have seen, can ever form part of our knowledge, till it has undergone this particular mental process, which we have called "reiteration." If the idea, or truth, intended to be communicated, be reiterated by the mind,--thought over again,--it will then be remembered:--but if it be not reiterated by the mind, it never can. It is also worthy of remark, that the tenacity with which the memory keeps hold of any idea or truth, depends greatly upon the vigour of the mind at the time, and still more perhaps upon the frequency of its reiteration. If a child, however languid, is forced to this act of reiteration of an idea but once, it will be remembered for a longer or a shorter time; but if his mind be vigorous and lively, and more especially if he can be made _repeatedly_ to reiterate the same idea in his mind at intervals, he will on that account, retain it much more tenaciously, and will have it at the command of the will more readily. Hence the vividness with which the scenes and the circumstances of youth arise upon the mind, and the tenacity with which the memory holds them. These scenes were of daily occurrence; and the small number of remarkable circumstances connected with childhood and youth having few rivals to compete with them in attracting the attention, were witnessed frequently with all the vigour and liveliness of the youthful mind, as yet unburdened with care. They