It is an acknowledged truth in philosophy that a just theory will always be confirmed by experiment.

If it be taught that all who are born have a right to support on the land, whatever be their number, and that there is no occasion to exercise any prudence in the affair of marriage so as to check this number, the temptations, according to all the known principles of human nature, will inevitably be yielded to, and more and more will gradually become dependent on parish assistance.

With regard to the duration of human life, there does not appear to have existed from the earliest ages of the world to the present moment the smallest permanent symptom or indication of increasing prolongation.

The world's population will multiply more rapidly than the available food supply.

Population, when unchecked, goes on doubling itself every 25 years or increases in a geometrical ratio.

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.

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.