thless, his remedy is an action to recover damages for a
breach of the warranty, and not an action to recover back the money
paid for the thing purchased.

A liability cannot be imposed on a person without his act or consent.
One man cannot force a benefit on another without his knowledge or
consent, and then compel him to pay for it. "If a person," says Clark,
"intentionally and knowingly performs services for another or
otherwise confers a benefit on him without his knowledge, so that he
has no opportunity to refuse the benefit, the law will not create a
liability to pay for it. So, where a person supplies another with
goods, the latter supposing that he is being supplied by another
person with whom he had contracted for the goods, the law will not
even imply a promise to pay for the goods." Where benefits are
conferred by one person on another under such circumstances as to
raise no promise in fact or in law to pay for them, he may,
nevertheless, become liable by retaining them. Thus, if a person were
to receive goods from another reasonably but mistakenly believing them
to be intended as a gift, and, after learning of his mistake, should
retain them, when he might return them, or if he should receive part
of the goods purchased from another, and retain them after failure of
the latter to supply the rest of the goods, the law would compel him
to pay for them. And the same rule applies where benefits are in any
other way received under such circumstances as to create no
contractual obligation, and are retained when they should in justice
be returned. If, however, the benefits thus received are incapable of
being returned, as where they consist of services, or of materials
which have been used in repairing a house, no liability is created.

=Sale.=--By a contract to sell goods the seller agrees to transfer the
property in them to the buyer for a consideration called the price.
There is an important distinction between a contract to sell in the
future and a present sale. The first is called an executory, the other
an executed, sale. If the goods are to be transferred, there is an
executed sale even though the price is not to be paid at the same
time. But if the price is paid, and the goods are not then to pass,
the transaction is a contract to sell, or an executory sale. Both
kinds of sales may be by deed or sealed contract as well as by parol
or orally.

Sales and contracts to sell are based on mutual assent, the