an is bound by a real obligation if he takes what is not
owed him from another who pays him by mistake; and the latter can, as
plaintiff, bring a condiction against him for its recovery, after the
analogy of the action whose formula ran 'if it be proved that he ought
to convey,' exactly as if the defendant had received a loan from him.
Consequently a pupil who, by mistake, is paid something which is not
really owed him without his guardian's authority, will no more be bound
by a condiction for the recovery of money not owed than by one for money
received as a loan: though this kind of liability does not seem to be
founded on contract; for a payment made in order to discharge a debt is
intended to extinguish, not to create, an obligation.

2 So too a person to whom a thing is lent for use is laid under a
real obligation, and is liable to the action on a loan for use. The
difference between this case and a loan for consumption is considerable,
for here the intention is not to make the object lent the property of
the borrower, who accordingly is bound to restore the same identical
thing. Again, if the receiver of a loan for consumption loses what he
has received by some accident, such as fire, the fall of a building,
shipwreck, or the attack of thieves or enemies, he still remains bound:
but the borrower for use, though responsible for the greatest care in
keeping what is lent him--and it is not enough that he has shown as much
care as he usually bestows on his own affairs, if only some one else
could have been more diligent in the charge of it--has not to answer for
loss occasioned by fire or accident beyond his control, provided it
did not occur through any fault of his own. Otherwise, of course, it is
different: for instance, if you choose to take with you on a journey a
thing which has been lent to you for use, and lose it by being attacked
by enemies or thieves, or by a shipwreck, it is beyond question that you
will be liable for its restoration. A thing is not properly said to
be lent for use if any recompense is received or agreed upon for the
service; for where this is the case, the use of the thing is held to be
hired, and the contract is of a different kind, for a loan for use ought
always to be gratuitous.

3 Again, the obligation incurred by a person with whom a thing is
deposited for custody is real, and he can be sued by the action of the
deposit; he too being responsible for the restoration of the identical