It is always easier to requite an injury than a service: gratitude is a burden, but revenge is found to pay.
A traitor is a betrayer – one who practices injury, while professing friendship. Benedict Arnold was a traitor, solely because, while professing friendship for the American cause, he attempted to injure it. An open enemy, however criminal in other respects, is no traitor.
One who is injured ought not to return the injury, for on no account can it be right to do an injustice; and it is not right to return an injury, or to do evil to any man, however much we have suffered from him.
If the other person injures you, you may forget the injury; but if you injure him you will always remember.