The histories of mankind are histories only of the higher classes.

No move towards the extinction of the passion between the sexes has taken place in the five or six thousand years that the world has existed.

[P]opulation, when unchecked, goes on doubling itself every twenty-five years, or increases in a geometrical ratio. ... [T]he means of subsistence, under circumstances the most favorable to human industry, could not possibly be made to increase faster than in an arithmetical ratio.

The exertions that men find it necessary to make, in order to support themselves or families, frequently awaken faculties that might otherwise have lain for ever dormant, and it has been commonly remarked that new and extraordinary situations generally create minds adequate to grapple with the difficulties in which they are involved.

The passion between the sexes has appeared in every age to be so nearly the same, that it may always be considered, in algebraic language as a given quantity.

Population trends have always provoked doom-fraught oracles, because their popular interpreters suppose that every new series will be infinitely sustained; yet, beyond the short term, expectations based on them are never fulfilled.

In general it may be said that demand is quite as necessary to the increase of capital as the increase of capital is to demand.