From all this it is obvious, that there is an essential difference between a child's acquiring the knowledge of things individually, and acquiring a knowledge of their several associations. The two must never, if possible, be confounded with each other. When they are kept distinct in the education of a child, he has an evident pleasure in attending to either; but as soon as they are allowed to interfere, and more especially when they are systematically blended together in the same exercise, he experiences confusion, irritation, and fatigue. There is no necessity, however, for this ever being the case. All that is required is, that the few individual elements that are to be grouped or associated in a lesson, whether they be objects or ideas, shall previously be made familiar to the pupil. These, when once known, may be brought before the mind of the child in any variety of order or form, and will be received readily and pleasantly, and will be retained by the memory without confusion, and without effort. By attention to these two principles, keeping each in its proper place, and bringing each to aid and uphold the other in its proper order, it will be found, that a child may be taught more real knowledge in one week, than is often communicated in other circumstances in the course of a year. CHAP. VII. _On the Acquisition of Knowledge by the Principle of Analysis, or Classification._ There is yet another principle brought into operation by Nature to enable her pupils to receive, to retain, and to make use of their knowledge. This is the principle of Classification, or Analysis.[6] The difference between this and the former principle described we think is sufficiently marked. The principle of Association, or Grouping, is carried on chiefly by means of the imagination, and begins to operate as soon as the mind is capable of imagining any thing; but the principle of Classification, or Analysis, is more intimately connected with the judgment. The consequence of this is, that it is but very partially called into action during the early stages of a child's education, and is never able to operate with vigour, till the reasoning powers of the pupil begin to develope themselves.