He exhausted the learning of the Development Theory. He studied and experimented up to the existing limits of knowledge on the question of the Origin of Life, and then poked out alone, as much farther as he could, into the ineffable black darkness that is close at the end of our noses on that, as well as most other questions. He hammered his way through the whole controversy on the Freedom of the Will. He mastered the whole works of Mrs. Henry C. Carey on one side, and of two hundred and fifty English capitalists and American college professors on the other, on the question of Protection or Free Trade. He made, with vast pains, an extensive collection of the questions proposed at debating societies and college-students’ societies with long Greek names. The last effort was a failure. Dr. Hicok had got the idea, that, from the spontaneous activity of so many free young geniuses, many wondrous and suggestive thoughts would be born. Having, however, tabulated his collection, he found, that, among all these innumerable gymnasia of intellect, there were only seventeen questions debated! The doctor read me a curious little memorandum of his conclusions on this unexpected fact, which will perhaps be printed some day. He investigated many other things too; for a sharp-witted little Presbyterian Scotch doctor, working to cheat the Devil out of his soul, can accomplish an amazing deal in twenty years. He even went so far as to take into consideration mere humbugs; for, if he could cheat the enemy with a humbug, why not? The only pain in that case, would be the mortification of having stooped to an inadequate adversary--a foeman unworthy of his steel. So he weighed such queries as the old scholastic _brocard, An chimoera bombinans in vacuo devorat secundas intentiones?_ and that beautiful moot point wherewith Sir Thomas More silenced the challenging schoolmen of Bruges, _An averia carrucae capta in vetito nomio sint irreplegibilia?_ He glanced a little at the subject of conundrums; and among the chips from his workshop is a really clever theory of conundrums. He has a classification and discussion of them, all his own, and quite ingenious and satisfactory, which divides them into answerable and unanswerable, and, under each of these, into resemblant and differential. For instance: let the four classes be distinguished with the initials of those four terms, A. R., A. D., U. R., and U. D.; you will find that the Infinite Possible Conundrum (so to speak) can always be reduced under one of those four heads. Using symbols, as they do in discussing syllogism--indeed, by the way, a conundrum is only a jocular variation in the syllogism, an intentional fallacy for fun (read Whately’s _Logic_, Book III., and see if it isn’t so)--using symbols, I say, you have these four “figures:”--