2. It is a rule, founded in common sense, that no one is bound to criminate himself. A witness may refuse to answer a question, when the answer would criminate him, and subject him to punishment. And a party in equity is not bound to answer a bill, when the answer would form a step in the prosecution. Coop. Eq. Pl. 204; Mitf. Eq. Pl. by Jeremy, 194; Story, Eq,. Pl. 591; 14 Ves. 59.