Esau is a man in the Old Testament: the son of Isaac, and the older twin of Jacob. The stories paint him as a hairy hunter, hungry and of the outdoors, while Jacob stays closer to the tents. The line students are meant to know is this: Esau came home starving, and he sold his birthright — the older son’s right to the family property and standing — to Jacob for a “mess of pottage,” that is, a bowl of stew Jacob had cooked. In later English, that scene became a saying: to sell your birthright for a mess of pottage is to throw away something large and lasting for a small, quick comfort. Though actually the Bible’s Esau is not only that one bargain; Jacob later also takes their father’s blessing by a trick, and the brothers’ story is longer and sadder than the proverb. You will meet the name in church, in literature, and in that old phrase more than in daily chat. It is a name, always capitalised.