“‘Mr. Lincoln, I thank you for this. It is the most splendid educational fact I ever happened upon. This is _genius_, with all its impulsive, inspiring, dominating power over the mind of its possessor, developed by education into _talent_, with its uniformity, its permanence, and its disciplined strength,--always ready, always available, never capricious,--the highest possession of the human intellect. But, let me ask, did you prepare for your profession?’ “‘Oh, yes! I “read law,” as the phrase is, that is, I became a lawyer’s clerk in Springfield, and copied tedious documents, and picked up what I could of law in the intervals of other work. But your question reminds me of a bit of education I had, which I am bound in honesty to mention. In the course of my law-reading, I constantly came upon the word _demonstrate_. I thought at first that I understood its meaning, but soon became satisfied that I did not. I said to myself, “What do I mean when I _demonstrate_ more than when I _reason_ or _prove_? How does _demonstration_ differ from any other proof?” I consulted Webster’s Dictionary. That told of “certain proof,” “proof beyond the possibility of doubt;” but I could form no idea what sort of proof that was. I thought a great many things were proved beyond a possibility of doubt, without recourse to any such extraordinary process of reasoning as I understood “demonstration” to be. I consulted all the dictionaries and books of reference I could find, but with no better results. You might as well have defined _blue_ to a blind man. At last I said, “Lincoln, you can never make a lawyer if you do not understand what _demonstrate_ means;” and I left my situation in Springfield, went home to my father’s house, and stayed there till I could give any proposition in the six books of Euclid at sight. I then found out what “demonstrate” means, and went back to my law-studies.’ “I could not refrain from saying, in my admiration at such a development of character and genius combined: ‘Mr. Lincoln, your success is no longer a marvel. It is the legitimate result of adequate causes. You deserve it all, and a great deal more. If you will permit me, I would like to use this fact publicly. It will be most valuable in inciting our young men to that patient classical and mathematical culture which most minds absolutely require. No man can talk well unless he is able first of all to define to himself what he is talking about. Euclid, well studied, would free the world of half its calamities, by banishing half the nonsense which now deludes and curses it. I have often thought that Euclid would be one of the best books to put on the catalogue of the Tract Society, if they could only get people to read it. It would be a means of grace.’ “‘I think so,’ said he, laughing; ‘I vote for Euclid.’