On the origin of the inequality among mankind

Of all human sciences the most useful and most imperfect appears to me to be that of mankind: and I will venture to say, the single inscription on the Temple of Delphi contained a precept more difficult and more important than is to be found in all the huge volumes that moralists have ever written. I consider the subject of the following discourse as one of the most interesting questions philosophy can propose, and unhappily for us, one of the most thorny that philosophers can have to solve. For how shall we know the source of inequality between men, if we do not begin by knowing mankind?...

I conceive two species of inequality among men; one which I call natural, or physical inequality, because it is established by nature, and consists in the difference of age, health, bodily strength, and the qualities of the mind, or of the soul; the other which may be termed moral, or political inequality, because it depends on a kind of convention, and is established, or at least authorized, by the common consent of mankind. This species of inequality consists in the different privileges, which some men enjoy, to the prejudice of others, such as that of being richer, more honoured, more powerful, and even that of exacting obedience from them...