It is not, then, an extensive territory that ruins nations; it is a diversity of instincts, a clashing of interests among the various parts of the population. When each province is isolated in feelings and interests from every other, no external foe is wanted to complete the ruin. Ambitious and adroit men will soon arise who know how to play upon these interests, and employ them for the promotion of their own schemes. Nations, in the various stages of their career, have often been compared to individuals. They have, it is said, their period of infancy, of youth, of manhood, of old age. But the similitude, however striking, is not extended further, and, while individuals die a natural death, nations are supposed always to come to a violent end. Probably, we do not like to concede that all nations, like all individuals, must ultimately die a natural death, even though no disease anticipates it; because we dislike to recognize a rule which must apply to us as well. Each nation fancies its own vitality imperishable. When we are young, we seldom seriously think of death; in the same manner, societies in the period of their youthful vigor and energy, cannot conceive the possibility of their dissolution. In old age and decrepitude, they are like the consumptive patient, who, while fell disease is severing the last thread that binds him to the earth, is still forming plans for years to come. Falling Rome dreamed herself eternal. Yet, the mortality of nations admits of precisely the same proof as that of individuals--universal experience. The great empires that overshadowed the world, where are they? The memory of some is perpetuated in the hearts of mankind by imperishable monuments; of others, the slightest trace is obliterated, the vaguest remembrance vanished. As the great individual intelligences, whose appearance marks an era in the history of human thought, live in the minds of posterity, even though no gorgeous tombstone points out the resting-place of their hull of clay; while the mausoleum of him whose grandeur was but temporary, whose influence transient only, carries no meaning on its sculptured surface to after ages; even so the ancient civilizations which adorned the globe, if their monuments be not in the domain of thought, their gigantic vestiges serve but to excite the wonder of the traveller and antiquary, and perplex the historian. Their sepulchres, however grand, are mute.[23]