From Li Shen's
李绅 Tang poem 《
悯农》 (Sympathy for the Farmer) II. Couplet:
谁知盘中餐，粒粒皆辛苦 - 'Who knows the food on the plate? - every single grain is toil.' The first of the two 《
悯农》 poems ends
四海无闲田，农夫犹饿死 ('though all the land is tilled, farmers still starve to death'). Taught to almost every Chinese primary-school child; quoted at nearly every 'clean your plate' campaign.
