But architecture is conventional, and demands a knowledge of its system and a mind informed as to the principles on which it depends for beauty. Hence, in the oldest temples of India and Egypt, there was probably vastness, without elegance or even embellishment. But no nation ever left structures that, in extent and grandeur, can compare with those of ancient Egypt; and these were chiefly temples. Nothing remains of the ancient monuments of Thebes but the ruins of edifices consecrated to the deity--neither bridges, nor quays, nor baths, nor theatres. It was when the Israelites were oppressed by Pharaoh that the great city of Heliopolis, which the Greeks called Thebes, arose, with its hundred gates, and stately public buildings, and magnificent temples. The ruins of these attest grandeur and vastness. They were built of stone, in huge blocks, and we are still at a loss to comprehend how such heavy stones could have been transported and erected. All the monuments of the Pharaohs are wonders of science and art, especially such as appear in the ruins of Carnack--a temple formerly designated as that of Jupiter Ammon. It was in the time of Sesostris, or Rameses the Great, the first of the Pharaohs of the nineteenth dynasty, that architecture in Egypt reached its greatest development. Then we find the rectangular cut blocks of stone in parallel courses, and the heavy piers, and the cylindrical column, with its bell-shaped capital, and the bold and massive rectangular architraves extending from pier to pier and column to column, surmounted by a deep covered coping or cornice. But the imposing architecture of Egypt was chiefly owing to the vast proportions of the public buildings. It was not produced by beauty of proportion, or graceful embellishments. It was designed to awe the people, and kindle sentiments of wonder and astonishment. So far as this end was contemplated, it was nobly reached. Even to this day the traveller stands in admiring amazement before those monuments which were old three thousand years ago. No structures have been so enduring as the Pyramids. No ruins are more extensive and majestic than those of Thebes. The temple of Carnack and the palace of Rameses the Great, were probably the most imposing ever built by man. This temple was built of blocks of stone seventy feet in length, on a platform one thousand feet long and three hundred wide, with pillars sixty feet in height. But this and other structures did not possess that unity of design, which marked the Grecian temples. Alleys of colossal sphinxes form the approach. At Carnack the alley was six thousand feet long, and before the main body of the edifice stand two obelisks commemorative of the dedication. The principal structures do not follow the straight line, but begin with pyramidical towers which flank the gateways. Then follows, usually, a court surrounded with colonnades, subordinate temples, and houses for the priests.