470 HARVARD LAW REVIEW. Th^ confusion arises largely (as pointed out supra) because of the anomalous doctrine laid down in Massachusetts and other States as to contributory negligence, and the consequent confusion be- tween that defence and Volenti non fit. But, as shown before, it is evident that it is only after reviewing all the facts and deciding that the plaintiff cannot be fairly said to have assumed the risks, knowing and appreciating the danger, that a jury is warranted in inquiring whether he was in exercise of due care in working or in his work. For it may be perfectly consistent with the existence of due care to work on a dangerous machine, and the most prudent men constantly do so ; and yet a man so doing may well be de- barred from an action, if injured, on the ground of assumption. To sum up: The duty which a master owes to his servant with regard to the care of his premises, or the machinery upon them, is practically identical with the duty which he owes to other persons who have gone upon his premises by invitation or for business,^ " It is the duty of all occupiers of real property to which others have right to resort upon business with the occupier, to use due care that those so resorting are not exposed to hidden dangers of which he is, or ought to be, aware, and of which they are ignorant, provided he has no good reason to presume that they have equal knowledge on the subject with himself," To this, in the case of servants, may be added the presumption that the servant knows the ordinary incidents of the business on which he engages when he enters the property of the master. As a foundation for show- ing no duty on his part, then, the master, like any occupier of premises, has only to show knowledge express or implied on the part of the servant. The defence Volenti then may arise. Limits of the Doctrine. It is evident that there must be some limit in actions of negli- gence to the defence. It cannot be that wherever a plaintiff knows there is some risk he debars himself from any right to com- plain if injury happens to him.^ A person does not necessarily assume the risk of the defendant's negligent action, even if he knows of it. Thus, if A. knows that B. drives his cab carelessly, and that he has run down many persons, A. does not necessarily 1 Cf. Bigelow on Torts, p. 328; Story on Agency, 9th ed., § 453 d, note i. 2 As Lord Halsbury, in Smith v. Baker, says, p. 337 : If this were so, "no person ought to have been awarded damages for being run down in London streets. . . . No person could have crossed London streets without knowing there was a risk of being run over."
