The study of the relation of organized society to individual sustenance may, for brevity, be called the science of social sustenance... The word "sustenance" means making a living, with or without a house or home, and with all that the term "living" implies when used in that way. Making a living is not merely keeping body and soul together. It is supplying all the physical, moral, and mental wants, in so far as conscious, irksome effort is required to supply them. What is a living to one man is not to another; but the man who makes his own living is always called self-sustaining. Sustenance, therefore, is the making any kind of a living.

Social sustenance is making a living as affected by social conditions. Social conditions are the conditions brought about by the existence and conduct of other people. Exactly what social sustenance means, then, is making a living as affected by the existence and conduct of other people.

The study of political economy begins the moment we try to think how our making a living is affected by other people...