Knowledge is received by the use of words in two ways,--either by oral speech, or by written language; but in both cases, the reception of the ideas is still governed by reiteration. We shall endeavour to examine the operation in both cases. Let us suppose that a teacher announces to a class of young children, that "Cain killed his brother Abel,"--and then examines the state of each child's mind in regard to it. All of them heard the words, but some only perhaps are now in possession of the truth communicated. Those who are so, followed the teacher in his announcement, not so much in reiterating the words, as in reiterating the idea,--the truth itself; and therefore it is, that they are now acquainted with the fact. Of those who heard, but have failed to add this truth to their stock of knowledge, there may be two classes;--those who attended to what was said, but failed to interpret the words; and those whose attention was not excited at all. Those who failed to interpret the words, or to extract the idea from them, reiterated the _words_ to themselves, and would perhaps be able to repeat the words again, but they do so in the same manner that a person reads or repeats words in an unknown tongue. The idea,--the truth,--is not yet perceived, and therefore cannot be remembered. The others who remember nothing, have reiterated nothing; their minds remained inactive. They also heard the words, but they failed to listen to them; in the same way as they often see objects, but do not look at them. Here it is evident that every child who reiterated the idea in his own mind, is in possession of the fact communicated; and all who did not do so, even although they reiterated the words, have no addition made to their knowledge; which shews that it is only by this act of the reiteration of the ideas, that any portion of our knowledge is ever acquired. That this is a correct exhibition of the principle, and a legitimate inference from the phenomena, may be still farther proved by an experiment similar to one formerly recommended. Let the teacher, in the middle of a story, ask some of the inattentive pupils a question respecting some of the persons or things he is speaking about, and force the reiteration of that part of the narrative in the child's mind by getting an answer, and it will be found at the close, that although he may remember nothing else of all that he heard, yet he will most perfectly remember that part about which he was questioned, and respecting which he returned an answer.