Thanksgiving, the Basics

Mevlana Jalaluddin Rumi on Gratitude
(from Discourses of Rumi, chapter 48, translated by A.J Arberry)

Gratitude for sucking the breast is a blessing. Though the breast be full, until you suck it the milk does not flow.

Someone asked: What is the cause of ingratitude, and what is it that prevents gratitude?The Master answered: The preventer of gratitude is inordinate greed. For whatever a man may get, he was greedy for more than that. It was inordinate greed that impelled him to that, so that when he got less than what he had set his heart upon his greed prevented him from being grateful. So he was heedless of his own defect, and heedless also of the defect and adulteration of the coin he proffered.
Raw and inordinate greed is like eating raw fruit and raw bread and raw meat; inevitably it generates sickness and begets ingratitude. When a man realises that he has eaten something unwholesome, a purge becomes necessary. God most High in His wisdom makes him suffer through ingratitude so that he may be purged and rid of that corrupt conceit, lest that one sickness become a hundred sicknesses.