Such a revolution is not the work of a day. Art requires time thus to inclose itself in mere mechanical dexterity. As a nation grows old, its art, like its literature, continually becomes more and more conventional. Every great period or school leaves to the generations that come after it types which have made a vivid impression upon taste and imagination. As time goes on these types become more numerous and more brilliant, and their prestige increases until it becomes little less than tyranny. Society can only escape from its thrall at the expense of some great religious or philosophical revolution, or by the infusion of new blood from without. And these changes western civilization had to undergo in the early centuries of our era, in the establishment of Christianity, the invasion of the barbarians, and the fall of the Roman Empire. Thanks to the peculiar circumstances of the country, Egyptian society was enabled to maintain the originality of its genius and the vitality of its institutions with unusual success. After each period of internal commotion or foreign invasion, the Egyptians set themselves to renew the chain of their national traditions. In spite of the foreign elements which had been received among them, the great mass of the people remained the same down to the latest days of antiquity. Heterogeneous constituents were absorbed by the nation without leaving any apparent trace. The ideas which the people had formed for themselves of the ultimate destiny of humanity were developed, indeed, and in successive ages varied slightly in general colour, but in none of their variations did they give rise to a new religion, as Brahmanism gave birth to Buddhism. As often as a new dynasty of kings succeeded in driving out the foreign conqueror and in re-establishing the unity of the kingdom, so often was there a complete restoration. The aim which they had in view was ever to restore, in all its parts, a _régime_ which was founded upon national pride. Enjoying a civilization which for ages had been alone in the world, it was in its full and glorious past that Egyptian society found the ideal to which it clung in spite of all obstacles and misfortunes. Its gaze was turned backwards towards those early sovereigns who seemed transfigured by distance, but whose presence in the memory kept alive the perpetual worship which had been vowed to them. [Illustration: FIG. 53.--Sculptor carving a statue, Thebes. (Champollion, pl. 180.)]