before it reaches the lowlands; the beds of the brooks have widened into
broad expanses of pebbles and gravel, over which, though in the hot
season passed dryshod, in winter sealike torrents thunder; the entrances
of navigable streams are obstructed by sandbars; and harbors, once marts
of an extensive commerce, are shoaled by the deposits of the rivers at
whose mouths they lie; the elevation of the beds of estuaries, and the
consequently diminished velocity and increased lateral spread of the
streams which flow into them, have converted thousands of leagues of
shallow sea and fertile lowland into unproductive and miasmatic
morasses.

Besides the direct testimony of history to the ancient fertility of the
now exhausted regions to which I refer--Northern Africa, the greater
Arabian peninsula, Syria, Mesopotamia, Armenia and many other provinces
of Asia Minor, Greece, Sicily, and parts of even Italy and Spain--the
multitude and extent of yet remaining architectural ruins, and of
decayed works of internal improvement, show that at former epochs a
dense population inhabited those now lonely districts. Such a population
could have been sustained only by a productiveness of soil of which we
at present discover but slender traces; and the abundance derived from
that fertility serves to explain how large armies, like those of the
ancient Persians, and of the Crusaders and the Tartars in later ages,
could, without an organized commissariat, secure adequate supplies in
long marches through territories which, in our times, would scarcely
afford forage for a single regiment.

It appears then, that the fairest and fruitfulest provinces of the Roman
Empire, precisely that portion of terrestrial surface, in short, which,
about the commencement of the Christian era, was endowed with the
greatest superiority of soil, climate, and position, which had been