12th Century medicine

From Cunnan

Blood Letting

Blood letting was a common practice to let of the energy of young men. For example, a literary hero Guingamor is to go hunting but:

Ses nies estoit ce jor seingniez,	His nephew [Guingamor] had been bled that day
Si estoit auques desetiez,	And so was feeling rather indisposed.

So Guingamor stays at home and plays chess.