The increase will be directly proportional to the means of subsistence.
Vice as a check to increase, is common to civilized and savage man, and limits population by artificial checks to conception, abortion, infanticide, disease, and war.

The third check, moral restraint, is peculiar to civilized man, and in the writings of Malthus, consists in restraint from marriage or simply delayed marriage.
Bonar says (Malthus and his Work, p.

53), "Moral restraint in the pages of Malthus, simply means continence which is abstinence from marriage followed by no irregularities." These checks have their origin in a need for, and scarcity of food,--food comprising all those conditions necessary to healthy life.
The need of food is vital and permanent.

The desire for food, immediate and prospective, is the first motive of all animal activity, but the amount of food available in the world is limited, and the possible increase of food is estimated by Malthus at an arithmetical ratio.
Whether or not this is an accurate estimate of the ratio of food increase is immaterial.

Malthus's famous progressions, the geometrical ratio of increase in the case of animals, and the arithmetical ratio of increase in the case of food, contain the vital and irrefutable truth of the immense disproportion between the power of reproduction in man and the power of production in food.
Under the normal conditions of life, the population tends constantly to press upon, and is restrained by the limits of food.