Meditations by Marcus Aurelius Book 9 Page 36

such a thing should be. But then especially, when thou dost find fault with either an unthankful, or a false man, must thou reflect upon thyself. For without all question, thou thyself art much in fault, if either of one that were of such a disposition, thou didst expect that he should be true unto thee: or when unto any thou didst a good turn, thou didst not there bound thy thoughts, as one that had obtained his end; nor didst not think that from the action itself thou hadst received a full reward of the good that thou hadst done.

For what wouldst thou have more? Unto him that is a man, thou hast done a good turn: doth not that suffice thee? What thy nature required, that hast thou done. Must thou be rewarded for it? As if either the eye for that it seeth, or the feet that they go, should require satisfaction.