We are commonly taught by experience, that all welldoing requireth gratitude. And even though the benefactor doth not covet it for himself, yet he should desire it, that the recipient may not suffer dishonour where the giver hath acquired virtuous merit. And such a special communion is there between these two acts, to wit, giving and thanking, that the first requireth the second by way of obligation. And did not the former exist, it would not be possible for there to be gratitude in the world. Wherefore, Saint Thomas who was the most clear teacher among the Doctors of Theology, saith in the second book of the second part of his work, in the 108th section, that every action returneth by nature to the cause from which it first proceeded. Therefore, since the giver is the chief cause of the benefit received by the other, it is requisite, by the ordinance of Nature, that the good he doth should come back to him in the shape of a fitting gratitude. And by this return we are enabled to understand the natural likeness between the works of Nature and those that give moral aid, for all things bring about a proper return, starting from a commencement and progressing till in the end they accomplish the recompence we speak of.