Now it is quite true that mother-wit and the common experiences of life do often furnish people with a sort of shrewd and sound judgment that carries them very creditably through the world. They come to good conclusions, though perhaps they would give bad reasons for them, if they were forced to find their reasons. But you cannot count upon mother-wit in everybody; perhaps not even in a majority. And then as for the experience of life,--there are a great many questions, and those of the deepest ultimate importance to mankind, in which the ordinary experience of life sheds no light, until it has been interrogated and interpreted by men with trained minds. 'It is far easier,' as has been said, 'to acquire facts than to judge what they prove.' What is done in our systems of training to teach people how to judge what facts prove? There is Mathematics, no doubt; anybody who has done even no more than the first book of Euclid's geometry, ought to have got into his head the notion of a demonstration, of the rigorously close connection between a conclusion and its premisses, of the necessity of being able to show how each link in the chain comes to be where it is, and that it has a right to be there. This, however, is a long way from the facts of real life, and a man might well be a great geometer, and still be a thoroughly bad reasoner in practical questions. Again, in other of your classes, in Chemistry, in Astronomy, in Natural History, besides acquiring groups of facts, the student has a glimpse of the method by which they were discovered, of the type of inference to which the discovery conforms, so that the discovery of a new comet, the detection of a new species, the invention of a new chemical compound, each becomes a lesson of the most beautiful and impressive kind in the art of reasoning. And it would be superfluous and impertinent for me here to point out how valuable such lessons are in the way of mental discipline, apart from the fruit they bear in other ways. But here again the relation to the judgments we have to form in the moral, political, practical sphere, is too remote and too indirect. The judgments, in this region, of the most brilliant and successful explorers in physical science, seem to be exactly as liable to every kind of fallacy as those of other people. The application of scientific method and conception to society is yet in its infancy, and the _Novum Organum_ or the _Principia_ of moral and social phenomena will perhaps not be wholly disclosed to any of us now alive. In any case it is clear that for the purposes of such an institution as this, if the rules of evidence and proof and all the other safeguards for making your propositions true and relevant, are to be taught at all, they must be taught not only in an elementary form, but with illustrations that shall convey their own direct reference and application to practical life. If everybody could find time to master