The state of art, in any community or nation, at any period of its history, depends upon a fortunate correspondence between two elements which we might call the internal and the external. By the former is meant the inner movement of mind or spirit, which must be of such depth and force as to leave a surplusage after the material needs of existence have been met. In every community where there is a certain degree of wealth, leisure and a vigorous movement of mind, this surplus force, remaining over after the necessary wheels of common life have been set in motion, will expend itself in some form of art or literature. The nature of the form selected as the expression of this surplus force will depend upon the fashion, the prevalent activity of the life of the day, or, in other words, the environment. Illustrating this principle, reference might be made to the condition of Greek art in the flowering time of its history, when the wealth of Athens was so great as to leave resources unemployed in the material uses of life, and when the intellectual movement was so splendid as to leave it until now a brilliant tradition of history. Only one form of art was pre-eminently successful here; it was sculpture, which at that time reached its fullest development--to such a degree that modern sculpture is only a weak repetition of ancient works in this line. So also the brilliant period of Italian painting, when the mental movement represented by Leonardo da Vinci, Michael Angelo, Lorenzo de Medici, and the pleasure-loving existence, the brilliant fetes, in which noble men and beautifully appareled women performed all sorts of allegorical representations, and the colors, groupings, etc., afforded the painter an endless variety of material and suggestion. When Rubens flourished in the Netherlands, a century later, similar conditions accompanied his appearance and the prolific manifestations of his genius. In the same way, music depends upon peculiar conditions of its own. They are three: The vigor of the mental movement in general, its strength upon the imaginative and sentimental side, and the suggestion from the environment in the way of musical instruments of adequate tonal powers. Such instruments never existed in the history of the art until about the sixteenth and seventeenth centuries. The organ, the violin and the predecessor of the pianoforte, the spinet, came to practical form at nearly the same time. At the same time the instruments of plucked strings--the guitars, lutes and other instruments which until then had occupied the exclusive attention of musicians--began to go out. Moreover, musical science had been worked out, and the arts of counterpoint, canonic imitation, fugue, harmony, etc., had all reached a high degree of perfection when Bach and Haendel appeared.