The Science Of Political Economy Is Essentially

No State Has Hitherto Existed (at Least That We Have Any Account Of) ... That No Check Whatever Has Existed To Early Marriages, Among The Lower Classes, From A Fear Of Not Providing Well For Their Families, Or Among The Higher Classes, From A Fear Of Lowering Their Condition In Life.

A Feather Will Weigh Down A Scale When There Is Nothing In The Opposite One.

Man Cannot Live In The Midst Of Plenty.

The Immediate Cause Of The Increase Of Population Is The Excess Of The Births Above Deaths; And The Rate Of Increase, Or The Period Of Doubling, Depends Upon The Proportion Which The Excess Of The Births Above The Deaths Bears To The Population.

The Doctrine Of Population Has Been Conspicuously Absent, Not Because I Doubt In The Least Its Truth And Vast Importance, But Because It Forms No Part Of The Direct Problem Of Economics.