Ingratitude is so dangerous to itself, and so detestable to other people, that nature, one would think, had sufficiently provided against it, without need of any other law. For every ungrateful man is his own enemy, and it seems superfluous to compel a man to be kind to himself, and to follow in his own inclinations. This, of all wickedness imaginable, is certainly the vice which does the most divide and distract human nature. Without the exercise and the commerce of mutual offices, we can be neither happy nor safe for it is only society that secures us: take us one by one, and we are a prey even to brutes as well as to one another.