§ 35. 2nd. Rousseau had himself little knowledge of mathematics and natural science, but he was strongly in favour of the “study of Nature”; and in his last years his devotion to botany became a passion. His curriculum for Émile is in the air, but the chief thing is to get him to attend to the phenomena of nature, and “to foster his curiosity by being in no hurry to satisfy it.” § 36. 3rd. About teaching and learning, there is one point on which we find a consensus of great authorities extending from the least learned of writers who was probably Rousseau to the most learned who was probably Friedrich August Wolf. In one form or other these assert that there is no true teaching but _self_-teaching. Past a doubt the besetting weakness of teachers is “telling.” They can hardly resist the tendency to be didactic. They have the knowledge which they desire to find in their pupils, and they cannot help expressing it and endeavouring to pass it on to those who need it, “like wealthy men who care not how they give.” But true “teaching,” as Jacotot and his disciple Joseph Payne were never tired of testifying, is “causing to learn,” and it is seldom that “didactic” teaching has this effect. Rousseau saw this clearly, and clearly pointed out the danger of didacticism. As usual he by exaggeration laid himself open to an answer that seems to refute him, but in spite of this we feel that there is valuable truth underlying what he says. “I like not explanations given in long discourses,” says he; “young people pay little attention to them and retain little from them. The things themselves! The things themselves! I shall never repeat often enough that we attach too much importance to words: with our chattering education we make nothing but chatterers.”[146] Accordingly Rousseau lays down the rule that Émile is not to learn science but to invent it (qu’il n’apprenne pas la science; qu’il l’invente); and he even expects him to invent geometry. As Émile is not supposed to be a young Pascal but only an ordinary boy with extraordinary _physical_ development such a requirement is obviously absurd, and Herbart has reckoned it among Rousseau’s _Hauptfehler_ (_Päd. Schriften_, ij., 242). The training prescribed is in fact the training of the intellectual athlete; and the trainer may put the body through its exercises much more easily than the mind. Of this the practical teacher is only too conscious, and he will accept Rousseau’s advice, if at all, only as “counsels of perfection.” Rousseau says: “Émile, obliged to learn of himself, makes use of his own reason and not that of others; for to give no weight to opinion, none must be given to authority; and the more part of our mistakes come less from ourselves than from other people. From this constant exercise there should result a vigour of mind like that which the body gets from labour and fatigue. Another advantage is that we advance only in proportion to our strength. The mind like