When the child has added a cognition to the primitive impulse which directs his attention to external things, he has acquired other relations with the world, other forms of interest; these are no longer merely those primitive ones which are bound up with a species of primordial instinct, but have become a discerning interest, based upon the conquests of the intelligence.
It is true that all these new conquests are fundamentally and profoundly based upon the psychical needs of the individual; but the intellectual element has now been added, transforming an impulse into a conscious and voluntary quest.
The old pedagogic conception, which assumed that to call the attention of the child to the unknown it is necessary to connect it with the known, because it is thus that his interest may be won for the new knowledge to be imparted, grasped but a single detail of the complex phenomenon we now witness after our experiments.
If the known is to represent a new source of interest directed towards the unknown, it is essential that it should itself have been acquired in accordance with the tendency of nature; then preceding knowledge will lend interest to objects of ever-increasing complexity and of lofty significance. The culture thus created ensures the possibility of an indefinite continuation in the successive evolution of such formative phenomena.
Moreover, this culture itself creates order in the mind: when the teacher, giving her plain and simple lesson, says: This is long, this is short, this is red, this is yellow, etc., she fixes with a single word the clearly marked order of the sensations, classifies, and "catalogues" them. And each impression is perfectly distinct from the other, and has its own determined place in the mind, which may be recalled by a word; thenceforth, new acquisitions will not be thrown aside or mixed together chaotically, but will be duly deposited in their proper places, side by side with previous acquisitions of the same kind, like books in a well-arranged library.
Thus the mind not only has within itself the propulsive force required to increase its knowledge, but also an established order, which will be steadily maintained throughout its successive and illimitable enrichment by new material; and as it grows and gains strength, it retains its "equilibrium." These continual exercises in comparison, judgment, and choice carried out among the objects, further tend to place the internal acquisitions so logically into relation one with another, that the results are a singular facility and accuracy of reasoning power, and a remarkable quickness of comprehension: the law of "the minimum of effort" is truly carried out as it is everywhere where order and activity reign.
The internal coordination, like physiological adaptation, establishes itself as a result of the spontaneity of the exercises; the free development of a personality which grows and organizes itself is that which determines such an internal condition, just as in the body of the embryo the heart, in process of development, makes a place for itself in the space of the diastinum between the lungs, and the diaphragm assumes its arched form as a result of pulmonary dilation.
The teacher directs these phenomena; but, in so doing, she is careful to avoid calling the child's attention to herself, since the whole future depends upon his concentration. Her art consists in understanding and in avoiding interference with natural phenomena.
That which has been clearly demonstrated as regards the nutrition of the new-born infant and the first coordinated activities of the spirit will be repeated at every period of life, with the necessary modifications induced by the increased complexity of the phenomena.
Continuing the parallel with physical nutrition, let us consider the growing infant which has cut its teeth, developed its gastric juice, and so gradually requires a more complicated diet, until we come to the adult man, nourishing himself by means of all the complications of modern kitchen and table; to keep himself in health, he should eat only the things which correspond to the intimate needs of his organism; and if he introduces over-rich or unusual, unsuitable or poisonous substances, the result will be impoverishment, self-poisoning, a "malady." Now it was the study of the child's nutrition during the period of suckling and during the first years of life which created alimentary hygiene, not only for the child but for the adult, and pointed out the perils to which all were alike exposed during the epoch when infantile hygiene was unknown.