The rule that witnesses could only swear to facts within their knowledge, coupled with the accident that these witnesses were not used in transactions which might create a debt, except for a particular fact, namely, the delivery of property, together with the further accident that this delivery was quid pro quo, was equivalent to the rule that, when a debt was proved by witnesses there must be quid pro quo. But these debts proved by witnesses, instead of by deed are what we call simple contract debts, and thus beginning with debt, and subsequently extending itself to other contracts, is established our peculiar and most important doctrine that every simple contract must have a consideration. This was never the law as to debts or contracts proved in the usual way by the defendant's seal, and the fact that it applied only to obligations which were formerly established by a procedure of limited use, [259] goes far to show that the connection with procedure was not accidental. The mode of proof soon changed, but as late as the reign of Queen Elizabeth we find a trace of this original connection. It is said, "But the common law requires that there should be a new cause (i. e. consideration), whereof the country may have intelligence or knowledge for the trial of it, if need be, so that it is necessary for the Public-weal." /1/ Lord Mansfield showed his intuition of the historical grounds of our law when he said, "I take it that the ancient notion about the want of consideration was for the sake of evidence only; for when it is reduced into writing, as in covenants, specialties, bonds, etc., there was no objection to the want of consideration." /2/ If it should be objected that the preceding argument is necessarily confined to debt, whereas the requirement of consideration applies equally to all simple contracts, the answer is, that in all probability the rule originated with debt, and spread from debt to other contracts. But, again, it may be asked whether there were no other contracts proved by witness except those which have been mentioned. Were there no contracts proved in that way to which the accidental consideration was wanting? To this also there is an easy answer. The contracts enforced by the civil courts, even as late as Henry II., were few and simple. The witness procedure was no doubt broad enough for all the contracts which were made in early times. Besides those of sale, loan, and the like, which have been mentioned, I find but two contractual [260] obligations. These were the warranties accompanying a sale and suretyship which was referred to at the beginning of the Lecture. Of the former, warranty of title was rather regarded as an obligation raised by the law out of the relation of buyer and seller than as a contract. Other express warranties were matters within the knowledge of the transaction witnesses, and were sworn to by them in Saxon times. /1/