DIVISIONS OF LAW. I91 mined by their will. The parties to an agreement not only con- fer and assume duties by their voluntary act, but by the same act prescribe what the duties shall be. The same remark applies to transactions involving agreement and obligation, though not usually included under the name of contract, such as the creation of trusts in English law. The parties can make a law for themselves just because their dis- positions are personal to themselves and do not impose or affect to impose any new duties on their fellow-subjects at large. Personal duties are also prescribed by rules of law attached to acts or relations of parties. Sometimes they are contemplated by the parties, though not within their control, and sometimes not. Thus in the case of marriage and other family relations the legal consequences are contemplated and accepted, but cannot be framed and varied at the will of the parties, Hke the duties created by a commercial contract.^ In many cases where duties resembling those created by contract are imposed by law (where, in Roman terms, there is obligation quasi ex co7itractti), they are such as it is considered that a just man, on being fully informed of the facts, would in the circumstances willingly assume. The most familiar example in this kind is the duty of returning a payment made by mistake. Where obligation arises from a merely wrongful act, the liability is of course not desired by the wrong-doer, and is contemplated, if at all, as an evil (from his point of view) to be endured only so far as it cannot be avoided. We have not yet mentioned another way in which personal duties and liabilities arise, namely, from the breach of antecedent personal d.uties created by agreement. Every such breach of duty is in some sense wrongful ; and it is contrary to the original intention of the parties. Agree- ments are made in order to be performed, not to be broken. It is even possible to regard the breach of a promise as a wrong in the strictest sense, a trespass or deceit.^ Still, there is a good deal of difference. Duties under agreement may easily be broken without any wrongful intention. Performance may be prevented by misadventure (which is not always an excuse even if the party 1 This does not apply to incidental dispositions of property such as are made by marriage settlements. These may well be treated, as in our law they are, as matters of agreement largely within the control of the parties. 2 This is fully exemplified in the history of the common law.
