While it appears to be a law of Nature, that there can be no accumulation of knowledge without the act of reiteration, yet there are other principles which she brings into operation in connection with it, by which the amount of the various branches of knowledge received is greatly increased, and the knowledge itself more easily comprehended, and more permanently retained upon the memory. The first of these principles, which we have before alluded to and described, is that of "individuation;" that principle by which an infant or child is induced to concentrate the powers of its mind upon a new object, and that to the exclusion for the time of every other, till it has become acquainted with it. In a former chapter we found, that as long as a child remains solely under the guidance of Nature, it will not allow its attention to be distracted by different _unknown_ objects at the same time; but whenever it selects one for examination, it invariably for the time abandons the consideration of every other. The consequence of this is, that infants, with all their physical and mental imbecility, acquire more real knowledge under the tuition of Nature in one year, than children who are double their age usually gain by the imperfect and unnatural exercises of unreformed schools in three or four. The cause of this is easily detected, and may be illustrated by the analogy of any one of the senses. The eye, for example, like the mind, must not only see the object, but it must look upon it--examine it--before the child can either become acquainted with it at the time, or remember it afterwards. But if unknown objects are made rapidly to flit past the eye of the child, so that this cannot be done before there is time to fix the attention upon any of them, the labour of the exhibitor is not only lost, but the sight of the child is impaired;--the eye itself is injured, and is less able, for some time afterwards, to look steadily upon any other object, even when that object is stationary. Such is the injury and the confusion created in the mind of a child when it is hurried forward from object to object, or from truth to truth, before the mind has had leisure to lay hold of them, or to concentrate its powers upon the ideas they suggest. The labour of the teacher in that case is not only lost, and the child harassed and irritated, but the powers of the mind, instead of being brightened and strengthened, are bewildered and mystified, and must therefore be weakened in a corresponding degree.