I must add, too, that there was an explicit theory of what was called Individuality among the Greeks; the phenomenon of the unaccountable differences of men from birth early attracted those sharp eyes, and the Stoics and others soon began to build in various directions from this basis. But just as the Greeks had a theory of harmony--though harmony was not developed until the last century--as Richter says somewhere that a man may contemplate the idea of death for twenty years, and only in some moment of the twenty-first suddenly have the realization of death come upon him, and shake his soul; so their theory of individuality must have been wholly amateur, not a working element, and without practical result. Surely, we seem in condition to say so with confidence if you run your minds back along this line of development which now comes to an end. For what have we done? We have interrogated Æschylus and Plato, whom we may surely call the two largest and most typic spirits of the whole Greek cultus, upon the main fact of personality; we have verified the abstract with the concrete by questioning them upon the most vital and well-known elements of personality: what do you believe about spiritual growth, about spiritual compactness, about true love, marriage, children, property? and we have received answers which show us that they have not yet caught a conception of what personality means, and that when they explicitly discuss individuality in their theories, it is a discussion of blind men about colors. VI. We are now to enter upon the second of our four lines of study by concentrating our attention upon three historic _details_ in the growth of this personality whose _general_ advance has been so carefully illustrated in our first line. These details are found in the sudden rise of Physical Science, of Modern Music, and of the Modern Novel, at periods of time so little separated from each other, that we may consider these great fields of human activity as fairly opened simultaneously to the entrance of man about the seventeenth and eighteenth centuries. Addressing ourselves first, then, to the idea of Science, let us place ourselves at a point of view from which we can measure with precision the actual height and nature of the step which man took in ascending from the plane of, say, Aristotle's "science" to that of Sir Isaac Newton's "science." And the only possible method of placing ourselves at this point of view is to pass far back and fix ourselves in the attitude which antiquity maintained towards physical nature, and in which succeeding ages comfortably dozed, scarcely disturbed even by Roger Bacon's feeble protest in the thirteenth century, until it was shocked out of all future possibility by Copernicus, Galileo and Sir Isaac Newton.