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

The prodigious waste of human life occasioned by this perpetual struggle for room and food, was more than supplied by the mighty power of population, acting, in some degree, unshackled, from the constant habit of emigration.

If I saw a glass of wine repeatedly presented to a man, and he took no notice of it, I should be apt to think that he was blind or uncivil. A juster philosophy might teach me rather to think that my eyes deceived me, and that the offer was not really what I conceived it to be.

The greatest talents have been frequently misapplied and have produced evil proportionate to the extent of their powers. Both reason and revelation seem to assure us that such minds will be condemned to eternal death, but while on earth, these vicious instruments performed their part in the great mass of impressions, by the disgust and abhorrence which they excited.

It does not, however, seem impossible that by an attention to breed, a certain degree of improvement, similar to that among animals, might take place among men. Whether intellect could be communicated may be a matter of doubt: but size, strength, beauty, complexion, and perhaps even longevity are in a degree transmissible... As the human race could not be improved in this way, without condemning all the bad specimens to celibacy, it is not probable, that an attention to breed should ever become general.

In a state therefore of great equality and virtue, where pure and simple manners prevailed, the increase of the human species would evidently be much greater than any increase that has been hitherto known.