It will be well to examine some of the earliest cases in which an undertaking (assumpsit) was alleged.  The first reported in the books is of the reign of Edward III. 3 The plaintiff alleged that the defendant undertook to carry the plaintiff’s horse safely across the Humber, but surcharged [276] the boat, by reason of which the horse perished.  It was objected that the action should have been either covenant for breach of the agreement, or else trespass.  But it was answered that the defendant committed a wrongful act when he surcharged the boat, and the objection was overruled.  This case again, although an undertaking was stated, hardly introduced a new principle.  The force did not proceed directly from the defendant, to be sure, but it was brought to bear by the combination of his overloading and then pushing into the stream.

The next case is of the same reign, and goes further. 1 The writ set forth that the defendant undertook to cure the plaintiff’s horse of sickness (manucepit equum praedicti W. de infirmirate), and did his work so negligently that the horse died.  This differs from the case of laming the horse with a nail in two respects.  It does not charge any forcible act, nor indeed any act at all, but a mere omission.  On the other hand, it states an undertaking, which the other did not.  The defendant at once objected that this was an action for a breach of an undertaking, and that the plaintiff should have brought covenant.  The plaintiff replied, that he could not do that without a deed, and that the action was for negligently causing the death of the horse; that is, for a tort, not for a breach of contract.  Then, said the defendant, you might have had trespass.  But the plaintiff answered that by saying that the horse was not killed by force, but died per def. de sa cure; and upon this argument the writ was adjudged good, Thorpe, J. saying that he had seen a man indicted for killing a patient by want of care (default in curing), whom he had undertaken to cure.

[277] Both these cases, it will be seen, were dealt with by the court as pure actions of tort, notwithstanding the allegation of an undertaking on the part of the defendant.  But it will also be seen that they are successively more remote from an ordinary case of trespass.  In the case last stated, especially, the destroying force did not proceed from the defendant in any sense.  And thus we are confronted with the question, What possible analogy could have been found between a wrongful act producing harm, and a failure to act at all?

I attempt to answer it, let me illustrate a little further by examples of somewhat later date.  Suppose a man undertook to work upon another’s house, and by his unskilfulness spoiled his employer’s timbers; it would be like a trespass, although not one, and the employer would sue in trespass on the case.  This was stated as clear law by one of the judges in the reign of Henry IV. 1 But