Ladies and gentlemen, I speak to you to-night as to persons assembled, somewhat, no doubt, for amusement, but still more for instruction. Institutions such as this were originally founded for the purpose of instruction; to supply to those who wish to educate themselves some of the advantages of a regular course of scholastic or scientific training, by means of classes and of lectures. I myself prize classes far higher than I do lectures. From my own experience, a lecture is often a very dangerous method of teaching; it is apt to engender in the mind of men ungrounded conceit and sciolism, or the bad habit of knowing about subjects without really knowing the subject itself. A young man hears an interesting lecture, and carries away from it doubtless a great many new facts and results: but he really must not go home fancying himself a much wiser man; and why? Because he has only heard the lecturer's side of the story. He has been forced to take the facts and the results on trust. He has not examined the facts for himself. He has had no share in the process by which the results were arrived at. In short, he has not gone into the real scientia, that is, the "knowing" of the matter. He has gained a certain quantity of second-hand information: but he has gained nothing in mental training, nothing in the great "art of learning," the art of finding out things for himself, and of discerning truth from falsehood. Of course, where the lecture is a scientific one, illustrated by diagrams, this defect is not so extreme: but still the lecturer who shows you experiments, is forced to choose those which shall be startling and amusing, rather than important; he is seldom or never able, unless he is a man of at once the deepest science and the most extraordinary powers of amusing, to give you those experiments in the proper order which will unfold the subject to you step by step; and after all, an experiment is worth very little to you, unless you perform it yourself, ask questions about it, or vary it a little to solve difficulties which arise in your own mind.