The man who has received great benefits from another person, may, by the natural coldness of his temper, feel but a very small degree of the sentiment of gratitude.
 Adam Smith, The Theory of Moral Sentiments (1759). copy citation

Context

“Many men behave very decently, and through the whole of their lives avoid any considerable degree of blame, who yet, perhaps, never felt the sentiment upon the propriety of which we found our approbation of their conduct, but acted merely from a regard to what they saw were the established rules of behaviour. The man who has received great benefits from another person, may, by the natural coldness of his temper, feel but a very small degree of the sentiment of gratitude. If he has been virtuously educated, however, he will often have been made to observe how odious those actions appear which denote a want of this sentiment, and how amiable the contrary. Though his heart therefore is not warmed with any grateful affection, he will strive to act as if it was, and will endeavour to pay all those regards and attentions to his patron which the liveliest gratitude could suggest.” source