It is requisite in English and American law for the formation of a simple contract that legally sufficient consideration be given for the promise or promises therein. This doctrine finds no close analogy in the Roman or modern Civil law. The history of the requirement is bound up with the history of the common-law action of assumpsit. ' Though certain parol contracts were recognized by the law prior to the rise of the action of assumpsit,1 yet it was only by means of that action that the formation of an infinite variety of contracts without a sealed writing, became possible, and after its development the kinds of parol agreements previously recognized were enforced generally by means of that action so that its requirements were applied to them. The action of assumpsit was originally a form of action on the case and regarded as Bounding in tort like the action of deceit. "The earliest cases in which an assumpsit was laid in the declaration were cases against a ferryman who undertook to carry the plaintiff's horse over the river, but who overloaded the boat, whereby the horse was drowned; against surgeons who undertook to cure the plaintiff or his animals, but who administered contrary medicines or otherwise unskilfully treated their patient; against a smith for laming a horse while shoeing it; against a barber who undertook to shave the beard of the plaintiff with a clean and wholesome razor, but who performed his work negligently and unskilfully to the great injury of the plaintiff's face; against a carpenter who undertook to build well and faithfully, but who built unskilfully." 2 From cases of misfeasance, like those just alluded to, the step was soon taken to cases of nonfeasance where the only wrong was a failure

1 See 8 Harv. L. Rev. 252, by Amen.

2The History of Assumpsit, 2 Harv.

L. Rev. 1, 2. In this and a succeeding article, ib53, Professor Ames definitively traced the early law on the subto do what had been promised. Somewhat later a promise to pay a precedent debt was enforced, the precedent debt, it was said, serving as consideration for the assumpsit. It will be seen that the consideration in these two classes of cases is entirely different. In the first class the gist of the action is an injury to the plaintiff caused by his entrusting his person or property to the defendant in reliance on the latter's promise or undertaking. The defendant is regarded as a tortfeasor because after assuming to act and inducing the plaintiff to change his position, he has negligently injured the plaintiff or his property, or has failed altogether to do as he agreed. In the second class of cases the thing which makes the defendant's promise enforceable is the precedent debt which originally arose in consequence of some benefit or quid pro quo received by the defendant, though not at the time the promise was made.3 It is from these two classes of cases that the frequently quoted alternative in definitions of consideration, a detriment to the plaintiff or a benefit to the defendant, is derived. Gradually the action of assumpsit became differentiated from other actions on the case and regarded as sounding in contract like covenant and debt, rather than tort.