tiveness, in its proper degree, is the secret of provision for the future and of all social progress. Where it is absent or deficient, we have the vices of improvidence and prodigality. When it appears in excessive strength, it gives rise to miserliness and hoarding for its own sake. Both in excess and defect it is socially injurious. (7) The sexual instinct is socially valuable only in its right degree. Excessive strength and undue weakness will equally lead to disastrous social results. (8) The same is true of the parental instinct.
Thus in the case of every instinct the "just right" degree is personally valuable and socially useful; while excess or defect in the strength of the instinct is disadvantageous.
It is the task of the moral educator to secure that these instincts shall be developed to the "just right" degree, and in the right directions. If one child is always eager to "punch" his neighbour, his excessive pugnacity must be restrained. If another is perpetually bored, his curiosity should be stimulated. If another suffers from excessive shyness, his self-assertiveness should be encouraged. In each case it should be the aim of the teacher to confirm the instinct in its "just right" degree. But a great difficulty arises here. What is the "just right" degree? The teacher may know quite well what is the "just right" degree of the instincts he possesses. He knows that they are "just right" precisely as he knows that the temperature of his bath is "just right." He does not require a thermometer, when he is healthy, to tell him when his bath is "just right"; and when he
