Of these four rules, the three last may be rules of duty, because they refer to things which are plainly, as a rule, at least, in the power of your will; but the first, if love be understood in its natural sense as referring to your feelings, is plainly only an ideal rule, since such feelings are obviously not directly under our own control, in the same way in which such actions as doing good to, blessing or praying for a person are so.