Rome, therefore, which came last in the succession, and swallowed up the three great powers that had _seriatim_ cast the human race into one mould, and had brought them under the unity of a single will, entered by inheritance upon all that its predecessors in that career had appropriated, but in a condition of far ampler development. Estimated merely by longitude and latitude, the territory of the Roman empire was the finest by much that has ever fallen under a single sceptre. Amongst modern empires, doubtless, the Spanish of the sixteenth century, and the British of the present, cannot but be admired as prodigious growths out of so small a stem. In that view they will be endless monuments in attestation of the marvels which are lodged in civilization. But considered in and for itself, and with no reference to the proportion of the creating forces, each of these empires has the great defect of being disjointed, and even insusceptible of perfect union. It is in fact no _vinculum_ of social organization which held them together, but the ideal _vinculum_ of a common fealty, and of submission to the same sceptre. This is not like the tie of manners, operative even where it is not perceived, but like the distinctions of geography--existing to-day, forgotten to-morrow--and abolished by a stroke of the pen, or a trick of diplomacy. Russia, again, a mighty empire, as respects the simple grandeur of magnitude, builds her power upon sterility. She has it in her power to seduce an invading foe into vast circles of starvation, of which the radii measure a thousand leagues. Frost and snow are confederates of her strength. She is strong by her very weakness. But Rome laid a belt about the Mediterranean of a thousand miles in breadth; and within that zone she comprehended not only all the great cities of the ancient world, but so perfectly did she lay the garden of the world in every climate, and for every mode of natural wealth, within her own ring-fence, that since that era no land, no part and parcel of the Roman empire, has ever risen into strength and opulence, except where unusual artificial industry has availed to counteract the tendencies of nature. So entirely had Rome engrossed whatsoever was rich by the mere bounty of native endowment.