To construct roads across and to cut avenues through the mountains an army of workmen, one hundred thousand in number, became necessary. The deep intervening valleys were filled up to the necessary level by the spoils rent from the lofty adjoining mountains, and where this could not be done, great bridges, supported on strong and high pillars, were thrown across from side to side. Elsewhere suspension bridges--"flying bridges," as the Chinese call them--were thrown across deep and rugged ravines, wide enough for four horsemen to travel abreast, their sides being protected by high balustrades. One of these, one hundred and fifty yards long, and thrown over a valley more than five hundred feet deep, is said to be still in perfect condition. These suspension bridges were built nearly two thousand years before a work of this character was attempted in Europe. In truth, the period in question, including several centuries before Christ, was the culminating age of Chinese civilization, in which appeared its great religious reformers, philosophers, and authors, its most daring engineers, and its monarchs of highest public spirit and broadest powers of conception and execution. It was the age of the Great Wall, the imperial system of highways, the system of canals (though the Great Canal was of later date), and other important works of public utility. By the strenuous labors described Kaotsou rendered his new capital easy of access from all quarters of the kingdom, while at frequent intervals along the great high-roads of the empire there were built post-houses, caravansaries, and other conveniences, so as to make travelling rather a pleasure than the severe task it formerly had been. The capital itself was made as attractive as the means of reaching it were made easy. Siaho, at once an able war minister and a great builder, planned for the emperor a palace so magnificent that Kaotsou hesitated in ordering its erection. Siaho removed his doubts with the following argument: "You should look upon all the empire as your family; and if the grandeur of your palace does not correspond with that of your family, what idea will it give of its power and greatness?" This argument sufficed: the palace was built, and Kaotsou celebrated its completion with festivities continued for several weeks. On one occasion during this period, uplifted with a full sense of the dignity to which he had attained, his pride found vent in the grandiloquent remark, "To-day I feel that I am indeed emperor, and perceive all the difference between a subject and his master."