THE general method to be pursued in the analysis of contract is the same as that already explained with regard to possession. Wherever the law gives special rights to one, or imposes special burdens on another, it does so on the ground that certain special facts are true of those individuals. In all such cases, therefore, there is a twofold task. First, to determine what are the facts to which the special consequences are attached; second, to ascertain the consequences. The first is the main field of legal argument. With regard to contracts the facts are not always the same. They may be that a certain person has signed, sealed, and delivered a writing of a certain purport. They may be that he has made an oral promise, and that the promisee has furnished him a consideration. The common element of all contracts might be said to be a promise, although even a promise was not necessary to a liability in debt as formerly understood. But as it will not be possible to discuss covenants further, and as consideration formed the main topic of the last Lecture, I will take up that first. Furthermore, as there is an historical difference between consideration in debt and in assumpsit, I shall confine myself to the latter, which is the later and more philosophical form.
It is said that any benefit conferred by the promisee on the promisor, or any detriment incurred by the promisee, [290] may be a consideration. It is also thought that every consideration may be reduced to a case of the latter sort, using the word "detriment" in a somewhat broad sense.
To illustrate the general doctrine, suppose that a man is desirous of having a cask of brandy carried from Boston to Cambridge, and that a truckman, either out of kindness or from some other motive, says that he will carry it, and it is delivered to him accordingly. If he carelessly staves in the cask, there would perhaps be no need to allege that he undertook to carry it, and on principle, and according to the older cases, if an undertaking was alleged, no consideration for the assumpsit need be stated. /1/ The ground of complaint in that case would be a wrong, irrespective of contract. But if the complaint was that he did not carry it as agreed, the plaintiff's difficulty would be that the truckman was not bound to do so unless there was a consideration for his promise. Suppose, therefore, that it was alleged that he promised to do so in consideration of the delivery to him. Would this be a sufficient consideration? The oldest cases, going on the notion of benefit to the promisor, said that it could not be, for it was a trouble, not a benefit. /2/ Then take it from the side of detriment. The delivery is a necessary condition to the promisor's doing the kindness, and if he does it, the delivery, so far from being a detriment to the promisee, is a clear benefit to him.
But this argument is a fallacy. Clearly the delivery would be sufficient consideration to enable the owner to declare in assumpsit for the breach of those duties which [291] arose, irrespective of contract, from the defendant's having undertaken to deal with the thing. /1/ It would be a sufficient consideration for any promise not involving a dealing with the thing for its performance, for instance, to pay a thousand dollars. /2/ And the law has not pronounced the consideration good or bad according to the nature of the promise founded upon it. The delivery is a sufficient consideration for any promise. /3/
The argument on the other side leaves out of sight the point of time at which the sufficiency of the consideration is to be determined. This is the moment when the consideration is furnished. At that moment the delivery of the cask is a detriment in the strictest sense. The owner of the cask has given up a present control over it, which he has a right to keep, and he has got in return, not a performance for which a delivery was necessary, but a mere promise of performance. The performance is still future. /4/
But it will be seen that, although the delivery may be a consideration, it will not necessarily be one. A promise to carry might be made and accepted on the understanding that it was mere matter of favor, without consideration, and not legally binding. In that case the detriment of delivery would be incurred by the promisee as before, but obviously it would be incurred for the sole purpose of enabling the promisor to carry as agreed.
[292] It appears to me that it has not always been sufficiently borne in mind that the same thing may be a consideration or not, as it is dealt with by the parties. The popular explanation of Coggs v. Bernard is, that the delivery was a consideration for a promise to carry the casks safely. I have given what I believe to be the true explanation, and that which I think Lord Holt had in view, in the fifth Lecture. /1/ But whether that which I have offered be true or not, a serious objection to the one which is commonly accepted is that the declaration does not allege that the delivery was the consideration.
The same caution should be observed in construing the terms of an agreement. It is hard to see the propriety of erecting any detriment which an instrument may disclose or provide for, into a consideration, unless the parties have dealt with it on that footing. In many cases a promisee may incur a detriment without thereby furnishing a consideration. The detriment may be nothing but a condition precedent to performance of the promise, as where a man promises another to pay him five hundred dollars if he breaks his leg. /2/
The courts, however, have gone far towards obliterating this distinction. Acts which by a fair interpretation of language would seem to have been contemplated as only the compliance with a condition, have been treated as the consideration of the promise. /3/ And so have counter promises in an agreement which expressly stated other matters as the consideration. /4/ So it should be mentioned, subject [293] to the question whether there may not be a special explanation for the doctrine, that it is said that an assignment of a leasehold cannot be voluntary under the statute of 27 Elizabeth, c. 4, because the assignee comes into the obligations of the tenant. /1/ Yet the assignee's incurring this detriment may not be contemplated as the inducement of the assignment, and in many cases only amounts to a deduction from the benefit conferred, as a right of way would be, especially if the only obligation is to pay rent, which issues out of the land in theory of law.
But although the courts may have sometimes gone a little far in their anxiety to sustain agreements, there can be no doubt of the Principle which I have laid down, that the same thing may be a consideration or not, as it is dealt with by the parties. This raises the question how a thing must be dealt with, in order to make it a consideration.
It is said that consideration must not be confounded with motive. It is true that it must not be confounded with what may be the prevailing or chief motive in actual fact. A man may promise to paint a picture for five hundred dollars, while his chief motive may be a desire for fame. A consideration may be given and accepted, in fact, solely for the purpose of making a promise binding. But, nevertheless, it is the essence of a consideration, that, by the terms of the agreement, it is given and accepted as the motive or inducement of the promise. Conversely, the promise must be made and accepted as the conventional motive or inducement for furnishing the consideration. The root of the whole matter is the relation of reciprocal [294] conventional inducement, each for the other, between consideration and promise.
A good example of the former branch of the proposition is to be found in a Massachusetts case. The plaintiff refused to let certain wood be removed from his land by one who had made an oral bargain and given his note for it, unless he received additional security. The purchaser and the plaintiff accordingly went to the defendant, and the defendant put his name upon the note. The plaintiff thereupon let the purchaser carry off the wood. But, according to the testimony, the defendant signed without knowing that the plaintiff was to alter his position in any way on the faith of the signature, and it was held that, if that story was believed, there was no consideration. /1/
An illustration of the other half of the rule is to be found in those cases where a reward is offered for doing something, which is afterwards done by a person acting in ignorance of the offer. In such a case the reward cannot be claimed, because the alleged consideration has not been furnished on the faith of the offer. The tendered promise has not induced the furnishing of the consideration. The promise cannot be set up as a conventional motive when it was not known until after the alleged consideration was performed. /2/
Both sides of the relation between consideration and promise, and the conventional nature of that relation, may be illustrated by the case of the cask. Suppose that the [295] truckman is willing to carry the cask, and the owner to let him carry it, without any bargain, and that each knows the other's state of mind; but that the truckman, seeing his own advantage in the matter, says to the owner, "In consideration of your delivering me the cask, and letting me carry it, I promise to carry it," and that the owner thereupon delivers it. I suppose that the promise would be binding. The promise is offered in terms as the inducement for the delivery, and the delivery is made in terms as the inducement for the promise. It may be very probable that the delivery would have been made without a promise, and that the promise would have been made in gratuitous form if it had not been accepted upon consideration; but this is only a guess after all. The delivery need not have been made unless the owner chose, and having been made as the term of a bargain, the promisor cannot set up what might have happened to destroy the effect of what did happen. It would seem therefore that the same transaction in substance and spirit might be voluntary or obligatory, according to the form of words which the parties chose to employ for the purpose of affecting the legal consequences.
If the foregoing principles be accepted, they will be seen to explain a doctrine which has given the courts some trouble to establish. I mean the doctrine that an executed consideration will not sustain a subsequent promise. It has been said, to be sure, that such a consideration was sufficient if preceded by a request. But the objections to the view are plain. If the request was of such a nature, and so put, as reasonably to imply that the other person was to have a reward, there was an express promise, although not put in words, and that promise was made at [296] the same time the consideration was given, and not afterwards. If, on the other hand, the words did not warrant the understanding that the service was to be paid for, the service was a gift, and a past gift can no more be a consideration than any other act of the promisee not induced by the promise.
The source of the error can be traced partially, at least, in history. Some suggestions touching the matter were made in the last Lecture. A few words should be added here. In the old cases of debt, where there was some question whether the plaintiff had showed enough to maintain his action, a "contract precedent" was spoken of several times as raising the duty. Thus, where a man had granted that he would be bound in one hundred shillings to pay his servant on a certain day for his services, and for payments made by the servant on his account, it was argued that there was no contract precedent, and that by parol the party is not obliged; and, further, that, so far as appeared, the payments were made by the servant out of his own head and at no request, from which no duty could commence. /1/
So when debt was brought on a deed to pay the plaintiff ten marks, if he would take the defendant's daughter to wife, and it was objected that the action should have been covenant, it was answered that the plaintiff had a contract precedent which gave him debt. /2/
The first case in assumpsit /3/ only meant to adopt this long familiar thought. A man went bail for his friend's servant, who had been arrested. Afterwards the master [297] promised to indemnify the bail, and on his failure to do so was sued by him in assumpsit. It was held that there was no consideration wherefore the defendant should be charged unless the master had first promised to indemnify the plaintiff before the servant was bailed; "for the master did never make request to the plaintiff for his servant to do so much, but he did it of his own head." This is perfectly plain sailing, and means no more than the case in the Year Books. The report, however, also states a case in which it was held that a subsequent promise, in consideration that the plaintiff at the special instance of the defendant had married the defendant's cousin, was binding, and that the marriage was "good cause... because [it] ensued the request of the defendant." Whether this was intended to establish a general principle, or was decided with reference to the peculiar consideration of marriage, /1/ it was soon interpreted in the broader sense, as was shown in the last Lecture. It was several times adjudged that a past and executed matter was a sufficient consideration for a promise at a later day, if only the matter relied on had been done or furnished at the request of the promisor. /2/
It is now time to analyze the nature of a promise, which is the
second and most conspicuous element in a simple contract. The
Indian Contract Act, 1872, Section 2,8 says:—
 
 "(a.) When one person signifies to another his willingness [298]
to do or to abstain from doing anything, with a view to obtaining
the assent of that other to such act or abstinence, he is said to
make a proposal:
 
 "(b.) When the person to whom the proposal is made signifies his
assent thereto, the proposal is said to be accepted. A proposal
when accepted becomes a promise."
According to this definition the scope of promises is confined to conduct on the part of the promisor. If this only meant that the promisor alone must bear the legal burden which his promise may create, it would be true. But this is not the meaning. For the definition is of a promise, not of a legally binding promise. We are not seeking for............