Matthew 5:6

They that hunger and thirst after righteousness (oi peinwnte kai dipswnte thn dikaiosunhn). Here Jesus turns one of the elemental human instincts to spiritual use. There is in all men hunger for food, for love, for God. It is passionate hunger and thirst for goodness, for holiness. The word for "filled" (cortasqhsontai) means to feed or to fatten cattle from the word for fodder or grass like Mark 6:39 "green grass" (corto clwro).