The past few centuries have deepened the conception of tolerance, given inner meaning as a virtue to what was originally only a convenience of social conduct. Tolerance in act has been proved practically advisable. It rests on the recognition that the intolerant Calvin, burning Servetus, was a more positively objectionable member of society than the Greek sage whose skepticism was so complete that he would commit himself to nothing more than the wagging of his finger. But if we are right in maintaining the incompatibility of tolerance and conviction, each gaining ground only at the expense of the other, are we not following the wrong star? Calvin was doubtless less pleasant to live with than the Greek skeptic; but, since clear definition of issues is the first step in judgment, the following of the harsher example may clear the way for those battles of thought which change the boundaries of its territories, when diplomacies accomplish nothing. Socrates, according to Plato, must have spent a good many hours and days in buttonholing young men on the streets of Athens, and pricking the airy bubbles of the catchwords which they used so glibly. His inveterate questioning often seemed to lead only to a deadlock. "What _is_ this justice, this temperance, this courage, of which you seem so sure?"--he would ask, and, after leading them a merry chase along the mazes of thought, brought them to the reluctant conclusion that virtue is not so simple, after all. There was something of the spirit of the detective in this sleuthing among ideas, this quick recognition and rejection of clues. What Socrates was chiefly trying to do--and no wonder he was accused of corrupting the young men!--was to cultivate in his interlocutors the rare art of questioning, to extirpate in them the prevalent stupidity of taking things for granted. But Socrates did not cure the world of using catchwords. In war, in politics, in religion, even in science, they still pass for the coin of the realm. They are always dangerous: for they always delude one into thinking to be easy that which is in truth most difficult. There is hardly a virtue which we can have without crowding out another virtue. We of the twentieth century have taken tolerance for granted, as if it were as much to be expected as good manners. And we have scarcely thought to ask the price for which it is bought.