It must be agreed that in most ages many countries have had part of their inhabitants in a state of slavery; yet it may be doubted whether slavery can ever be supposed the natural condition of man. It is impossible not to conceive that men in their original state were equal; and very difficult to imagine how one would be subjected to another but by violent compulsion. An individual may, indeed, forfeit his liberty by a crime; but he cannot by that crime forfeit the liberty of his children.

September 23, 1777, p. 363 - Life of Samuel Johnson (1791) - Vol III