his drunkenness, or
keeps them after becoming sober, he is liable. Intoxication only renders
a contract voidable, not void, as the party intoxicated may adopt it on
recovering his understanding.

Sec.5. Another requisition to a valid contract, is the _mutual assent of
the parties_. A mere offer by one party not assented to or accepted by
the other, constitutes no contract. Assent must also be given freely. A
contract entered into under duress, or compulsion, is not binding; as
where assent is extorted by threats of personal injury. Assent must also
be given with a knowledge of facts. A contract made under an injurious
mistake, or ignorance of a material fact, may be avoided, even though
the fact is not fraudulently concealed. But a mistake made through
ignorance of the law, will not render a contract void.

Sec.6. A _valuable consideration_ also is necessary to a valid contract. A
_consideration_ is what is given or done, or to be given or done, as the
cause or reason for which a person enters into an agreement. Thus, the
money given or offered, for which a man agrees to perform certain labor,
is the consideration of the agreement. So the money or other thing for
which a promissory note is given, is the consideration. A valuable
consideration is any thing that is either a benefit to the party
promising, or some trouble or injury to the party to whom the promise is
made.

Sec.7. Mutual promises are sufficient considerations to make a contract
binding; but they must be made at the same time. Such promises support
each other. The promise of one party constitutes a sufficient
consideration for a promise by the other party. In case the parties are
distant from each other, if the proposition is made in writing and sent
by mail, and a letter of acceptance is written and put in the mail, the
contract is complete, unless, before mailing the letter of acceptance,
a second letter has been received containing a retraction of the
proposal.

Sec.8. Promises which are wholly gratuitous are void; because, being
neither a benefit to the promiser, nor an injury to the promisee, they
are not regarded in law as a valuable consideration. Hence,
subscriptions to public works and charitable, literary, and religious
institutions, if they are merely gratuitous, can not be collected,
unless they have operated to induce others to advance money, make
engagements, or do other acts to their own injury.

Sec.9. As gratuitous promises are void f