There is another circumstance connected with the operation of this principle in the young, which is of importance. Almost the whole of a child's knowledge is composed of these groupings. Before the developement of the reasoning powers, by which the individual is enabled to _classify_ the elements of his knowledge, there is no way of remembering these elements in connection with each other, except by this principle. If, therefore, we change the order or relative position of the elements or objects which compose the scene, or group, we draw the attention of the pupil altogether from the former, and create another which is entirely new;--in the same way as the transposition of the figures in any sum, forms another of an entirely different amount. The drawing-room, for example, is seen by the children of the family with the fire-place, the cabinet, the sofas, the tables, and other stationary ornaments, in certain relative positions, and this grouping of those objects is to them in reality all that they know of the room. Any material change in shifting these objects to other places in the apartment, would, to the _parent_, whose judgment is ripened, produce feelings comparatively slight; but, to the younger branches of the family who group, but cannot as yet classify, it would appear like the complete annihilation of the former apartment. The different arrangement of a few of the articles only, would to them create another, and an entirely different room. This leads us to observe another circumstance connected with the operation of this principle, in the instruction of the young, which is the remarkable fact, that, by making the child familiar with a very few primitive elements, a parent or teacher may communicate an almost infinite variety of groupings, or stories, for cultivating the mind, and increasing the knowledge of his pupil. Hence it is, that hundreds of agreeable and useful little histories have been composed for children, with no other machinery than a mamma and her child, and the occasional introduction of a doll or a dog, a cat or a canary bird. To the child, there is in these numerous groupings no appearance of sameness, nor want of variety; and although so much circumscribed in their original elements, they never fail to amuse and delight. The most important circumstance, however, connected with the working of this principle in the education of the young, appears to be the necessity of a previous familiarity with the individual objects, before the child is called upon to group them. If this has been attended to, the grouping of these into any combination will be easy and pleasant;--but if his attention be called from the group, to examine exclusively even but one of its elements, the operation is checked, the mind becomes confused, its powers are weakened, and the grouping has again to commence under serious disadvantages.