We are accustomed to associate with the names of the great men of all times and in all lines of activity, certain dominant characteristics and traits of personality, which, though usually merely coincident and contributing factors, serve none the less as the tangible facts whereby the mind is enabled to grasp and gauge their power. It is a criterion whose insufficiency becomes evident only in the isolated instances wherein such natural indices of character are made conspicuous chiefly by their absence. There are characters in history upon which the test of time has set its seal of greatness, but which, considered abstractly and apart from their achievements, seem merely negative and colorless. Their work remains as the tangible evidence of their genius, yet any effort to establish the relation of cause and effect between that work and the intrinsic personality of its author is uniformly unsatisfactory in its results.