The causes which destroyed the ancient republics were numerous; but in Rome, one principal cause was the vast inequality of fortunes.
Even fairly good students, when they have obtained the solution of the problem and written down neatly the argument, shut their books and look for something else. Doing so, they miss an important and instructive phase of the work. . . . A good teacher should understand and impress on his students the view that no problem whatever is completely exhausted.