In all this we ought simply to take our lessons from Nature, if we wish to succeed in conveying knowledge by the combination of simple objects. In the above example, we have seen that a single glance was sufficient to give the infant a distinct idea of the whole scene; and the reason is, that the principle of individuation had previously done its work. Each of the elements of which the scene was composed, had undergone an individual and separate examination, and therefore each was familiar. This is Nature's method of communicating knowledge to the young; and it is obvious, that a different arrangement of the objects or actions would have made no difference in the effects produced by the operation of the principle. Whatever the circumstances might have been, the new scene, with all its variety of incidents, persons, and things, which it would take ten-fold more time to enumerate than to learn, would at once be impressed on the mind, and delivered over to the keeping of the memory, without labour, or any perceptible effort. The whole grouping forms a chain of circumstances, any one link in which, when afterwards laid hold of by the mind, brings up all the others in connection with it. The memory by this means is relieved from the burden of remembering all the individualities, and the innumerable details of the scene, by maintaining a comprehensive hold of the whole united group, as one undivided object for remembrance. From this it appears evident, that this principle is intended to succeed that of individuation, and never to precede it. Objects and truths which form the elements of knowledge must be individually familiar, before they can be successfully grouped, or associated together in masses, in the way in which the several parts of the knowledge of the young are usually presented; but after these objects or truths have once become known, they may be permanently associated together in any variety of form without fatigue, and be retained on the memory for use without confusion or distraction of any kind. In our investigations into the nature and working of this principle, as detailed in a former chapter, we found several causes which gave rise to certain uniform effects, which, for the purpose of imitation or avoidance, may be classed under the following heads:--We found, 1. That wherever the principle of grouping acted with effect, it had always been preceded by the principle of individuation. 2. That wherever the principle of individuation was made to interfere, the effect intended by the principle of association was in the same degree obstructed or destroyed. 3. That whenever ideas or objects, whether known or unknown, were presented to a child in greater number than the mind could receive or reiterate them, it silently dropped the surplus;--but if these were _forced_ upon the mind, all the mischiefs arising from the interference of the two hostile principles immediately took place.