ssumed, as the foundation of the jurisdiction, that the plaintiff had
been induced by the defendant's undertaking, and with the defendant's
consent, to alter his position for the worse in some way. He had paid or
bound himself to pay money, he had parted with goods, he had spent time
in labour, or he had foregone some profit or legal right. If he had not
committed himself to anything on the strength of the defendant's
promise, he had suffered no damage and had no cause of action.
Disappointment of expectations is unpleasant, but it is not of itself
_damnum_ in a legal sense. To sum up the effect of this in modern
language, the plaintiff must have given value of some kind, more or
less, for the defendant's undertaking. This something given by the
promisee and accepted by the promisor in return for his undertaking is
what we now call the _consideration_ for the promise. In cases where
debt would also lie, it coincides with the old requirement of value
received (_quid pro quo_) as a condition of the action of debt being
available. But the conception is far wider, for the consideration for a
promise need not be anything capable of delivery or possession. It may
be money or goods; but it may also be an act or series of acts; further
(and this is of the first importance for our modern law), it may itself
be a promise to pay money or deliver goods, or to do work, or otherwise
to act or not to act in some specified way. Again, it need not be
anything which is obviously for the promisor's benefit. His acceptance
shows that he set some value on it; but in truth the promisee's burden,
and not the promisor's benefit, is material. The last refinement of
holding that, when mutual promises are exchanged between parties, each
promise is a consideration for the other and makes it binding, was
conclusively accepted only in the 17th century. The result was that
promises of mere bounty could no more be enforced than before, but any
kind of lawful bargain could; and there is no reason to doubt that this
was in substance what most men wanted. Ancient popular usage and feeling
show little more encouragement than ancient law itself to merely
gratuitous alienation or obligations. Also (subject, till quite modern
times, to the general rule of common-law procedure that parties could
not be their own witnesses, and subject to various modern statutory
requirements in various classes of cases) no particular kind of proof
was necessary. The necessity o