“A man,” it is argued, “who has received a benefit, however gratefully he may have received it, has not yet accomplished all his duty, for there remains the part of repayment; just as in playing at ball it is something to catch the ball cleverly and carefully, but a man is not called a good player unless he can handily and quickly send back the ball which he has caught.” This analogy is imperfect; and why? Because to do this creditably depends upon the movement and activity of the body, and not upon the mind: and an act of which we judge entirely by the eye, ought to be all clearly displayed. But if a man caught the ball as he ought to do, I should not call him a bad player for not returning it, if his delay in returning it was not caused by his own fault. “Yet,” say you, “although the player is not wanting in skill, because he did one part of his duty, and was able to do the other part, yet in such a case the game is imperfect, for its perfection lies in sending the ball backwards and forwards.” I am unwilling to expose this fallacy further; let us think that it is the game, not the player that is imperfect: so likewise in the subject which we are discussing, the thing which is given lacks something, because another equal thing ought to be returned for it, but the mind of the giver lacks nothing, because it has found another mind equal to itself, and as far as intentions go, has effected what it wished.