The consent of the parties to a contract must be: 1. Free; 2. Mutual; and, 3. Communicated by each to the other. Ca. Civ. Code § 1565 Enacted 1872.
Consent is not mutual, unless the parties all agree upon the same thing in the same sense. But in certain cases defined by the Chapter on Interpretation, they are to be deemed so to agree without regard to the fact. Ca. Civ. Code § 1580 Enacted 1872.