Defectives are an additional burden to the State.

How shall population be so regulated as to established an equilibrium between the stability of the State, and the highest well-being of the citizens?
The combined philosophy of the Greeks counselled the encouragement of the best citizens to increase their kind, and the practice of the exposure of infants and abortion.
A century of debate has raged round the name of Malthus, the great modern analyst of the population problem.

He published his first essay on population in 1798, a modest pamphlet, which fed so voraciously on the criticism supplied to it, that it developed into a mighty contribution to a great social problem, second only in time and in honour to the work of his great predecessor in economic studies, Adam Smith.
Malthus's first essay defined and described the laws of multiplication as they apply only to the lower animals and savage man.

It was only in his revised work, published five years later, that he described moral restraint as a third check to population.
Adverse criticism had been bitter and severe, and Malthus saw that his first work had been premature.

He went to the continent to study the problem from personal observation in different countries.