importation, and allowing some variation for the prevalence of
luxury, or of frugal habits, that population constantly bears a
regular proportion to the food that the earth is made to produce.
In the controversy concerning the populousness of ancient and
modern nations, could it be clearly ascertained that the average
produce of the countries in question, taken altogether, is
greater now than it was in the times of Julius Caesar, the
dispute would be at once determined.

When we are assured that China is the most fertile country in
the world, that almost all the land is in tillage, and that a
great part of it bears two crops every year, and further, that
the people live very frugally, we may infer with certainty that
the population must be immense, without busying ourselves in
inquiries into the manners and habits of the lower classes and
the encouragements to early marriages. But these inquiries are of
the utmost importance, and a minute history of the customs of the
lower Chinese would be of the greatest use in ascertaining in
what manner the checks to a further population operate; what are
the vices, and what are the distresses that prevent an increase
of numbers beyond the ability of the country to support.

Hume, in his essay on the populousness of ancient and modern
nations, when he intermingles, as he says, an inquiry concerning
causes with that concerning facts, does not seem to see with his
usual penetration how very little some of the causes he alludes
to could enable him to form any judgement of the actual
population of ancient nations. If any inference can be drawn from
them, perhaps it should be directly the reverse of what Hume
draws, though I certainly ought to speak with great diffidence in