Philip Stanhope, 4th Earl of Chesterfield Quote

In order to judge of the inside of others, study your own; for men in general are very much alike, and though one has one prevailing passion, and another has another, yet their operations are much the same; and whatever engages or disgusts, pleases, or offends you in others will engage, disgust, please or offend others in you.

The Works of Lord Chesterfield (ed. 1855)