In 1860, sixty-three per cent of the couples married in Great Britain had families of four or more children; in 1925 only twenty per cent had more than four.

The germs of existence contained in this spot of earth, with ample food, and ample room to expand in, would fill millions of worlds in the course of a few thousand years.

The main peculiarity which distinguishes man from other animals is the means of his support - the power which he possesses of very greatly increasing these means.

Subsistence increases only in an arithmetical ratio.

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

Had population and food increased in the same ratio, it is probable that man might never have emerged from the savage state.

The finest minds seem to be formed rather by efforts at original thinking, by endeavours to form new combinations, and to discover new truths, than by passively receiving the impressions of other men's ideas.