So much, then, concerning the limits of verbal communication. Words, we say, are not vehicles. No perception, no mental possession, passes from mind to mind. You can impart to another no piece of knowledge whose main elements were not already in his mind, no thought which was not substantially existent in his consciousness before your voice began to seek his ear. Instructors may, indeed, put a pupil in the way to obtain fresh perceptions, and more rarely a wise man may put an apt disciple in the way to obtain deeper insights; but, after all, the learner must _learn_; the learner must for himself behold the fact, with the eyes of body or of soul; and he must behold it as it is in itself, not merely as it is in words. Hence the new scheme of school-education. Agassiz says, in substance,--"If you would teach a boy geography, take him out on the hills, and make the earth herself his instructor. If you would teach him respecting tigers or turtles, _show_ him tiger or turtle. Take him to a Museum of Natural History; let him always, so far as possible, learn about facts from the facts themselves." Judicious and important advice. And the basis of it we find in what has been set forth above, namely, that words convey no perception, whether of physical or of spiritual truth. It follows, therefore, that only he whose soul is eloquent within him will gain much from any eloquence of his fellow. Only he whose heart is a prophet will hear the prophet. A divine preparation of the nature, divine activities of the soul, precede all high uses of communication. Though Demosthenes or Phillips speak, it is the hearer's own spirit that convinces him. Conviction cannot be forced upon one from without. Hence the well-known futility of belligerent controversy. No possible logic will lead a man ahead of his own intelligence; neither will any take from him the persuasions which correspond to his mental condition. A good logical _pose_ may sometimes serve to lower the crest of an obstreperous sophist, as boughs of one species of ash are said to quell the rattlesnake; but with both these sinuous animals the effect is temporary, and the quality of the creature remains unchanged. Even though one be sincerely desirous of advancing his intelligence, it is seldom, as Mr. Emerson has somewhere said, of much use for him to carry his questions to another. He of whom insight is thus asked may be sage, eloquent, apt to teach; but it will commonly be found, nevertheless, that his words, for some reason, do not seem to suit the case in hand: admirable words they are, perhaps, for some cases closely analogous to this, it may be for all such cases, and it is a thousand pities that the present one does not come within their scope; but this, as ill luck will have it, is that other case which they do _not_ fit.