A rather cynical but beautifully expressed view from Goldsmith, a very proud and vain man.
Gratitude and love are almost opposite affections: love is often an involuntary passion, placed upon our companions without our consent, and frequently conferred without our previous esteem. We love some men we know not why; our tenderness is naturally excited in all their concerns; we excuse their faults with the same indulgence and approve their virtues with the same applause with which we consider our own. While we entertain the passion, it pleases us, we cherish it with delight, and give it up with reluctance, and love for love is all the reward we expect or desire.
Gratitude, on the contrary, is never conferred but where there have been previous endeavours to excite it; we consider it as a debt, and our spirits wear a load till we have discharged the obligation. Every acknowledgment of gratitude is a circumstance of humiliation; and some are found to submit to frequent mortifications of this kind, proclaiming what obligations they owe, merely because they think it in some measure cancels the debt.
Thus love is the most easy and agreeable, and gratitude the most humiliating affection of the mind: we never reflect on the man we love, without exulting in our choice, while he who has bound us to him by benefits alone, rises to our ideas as a person to whom we have in some measure forfeited our freedom.
Oliver Goldsmith: Citizen of the World, Letter LXVI.