Among the real disciples of the Florentine, the following were the chief:--Raphael di Monte Lupo, a favorite pupil, who assisted his master in the tomb of Julius, the greatest undertaking in modern sculpture, if completed; Nicolo di Tribulo, an excellent founder, by whom are the bronze doors of the cathedral at Bologna; Giovanni del Opera, whose name is significant of his industry; Danti, the closest imitator of his instructer. Ammanati subsequently transferred his attention to architecture. Giovanni di Bologna, a Frenchman by birth, an Italian as a sculptor, was the most eminent of all the scholars of Michael Angelo; and, on the death of the latter, continued to be the leading master in Europe till the end of the century. Beyond the confines of Italy, the art had yet made few advances worthy of notice; and what little had been accomplished was upon the principles of the Tuscan school. Thus, at the close of the sixteenth century, the genius and principles of Michael Angelo extended their influence over the whole of Europe. During the last thirty years of this era, however, the art had been on the decline. These principles could be maintained only by that genius by which they had been invented and matured; and by it alone could the errors of the system be consecrated or concealed. CHAPTER VIII. THE seventeenth century thus rose with few favorable presages for sculpture. The Group of Hercules and the Centaur, set up in Florence the last year of the former era, serves to show a considerable falling off in the intellectual qualities, while it displays also many improvements and facilities introduced into the technical principles and modes of mechanical operation. These are the last beauties to linger in the lapse of talent. External circumstances, also, both moral and political, had become less favorable. The states of Italy were either no longer alive to the same motives which had induced a cultivation of sculpture, or, with the loss of liberty, had lost also the desire of prosecuting the measures of public aggrandizement. The ascendancy of painting, likewise, was hostile to the recovery of a manly and accurate style of design in the sister art; while the spirit of philosophical inquiry, which came abroad in the seventeenth century, was inimical to the fine arts generally. It must, however, be acknowledged, that the great sources of decline originated in the state of the art itself. Indeed, when a high degree of excellence has been attained in any art, a rapid and sudden retrogression will always be found to indicate the operation of external influences; at the same time, such falling off must always be preceded by, and is in part the result of, internal corruption in the principles of composition or of criticism.