If, now, the ordinary liabilities in tort arise from failure to comply with fixed and uniform standards of external conduct, which every man is presumed and required to know, it is obvious that it ought to be possible, sooner or later, to formulate these standards at least to some extent, and that to do so must at last be the business of the court. It is equally clear that the featureless generality, that the defendant was bound to use such care as a prudent man would do under the circumstances, ought to be continually giving place to the specific one, that he was bound to use this or that precaution under these or those circumstances. The standard which the defendant was bound to come up to was a standard of specific acts or omissions, with reference to the specific circumstances in which he found himself. If in the whole department of [112] unintentional wrongs the courts arrived at no further utterance than the question of negligence, and left every case, without rudder or compass, to the jury, they would simply confess their inability to state a very large part of the law which they required the defendant to know, and would assert, by implication, that nothing could be learned by experience. But neither courts nor legislatures have ever stopped at that point. From the time of Alfred to the present day, statutes and decisions have busied themselves with defining the precautions to be taken in certain familiar cases; that is, with substituting for the vague test of the care exercised by a prudent man, a precise one of specific acts or omissions. The fundamental thought is still the same, that the way prescribed is that in which prudent men are in the habit of acting, or else is one laid down for cases where prudent men might otherwise be in doubt. It will be observed that the existence of the external tests of liability which will be mentioned, while it illustrates the tendency of the law of tort to become more and more concrete by judicial decision and by statute, does not interfere with the general doctrine maintained as to the grounds of liability. The argument of this Lecture, although opposed to the doctrine that a man acts or exerts force at his peril, is by no means opposed to the doctrine that he does certain particular acts at his peril. It is the coarseness, not the nature, of the standard which is objected to. If, when the question of the defendant's negligence is left to a jury, negligence does not mean the actual state of the defendant's mind, but a failure to act as a prudent man of average intelligence would have done, he is required to conform to an objective standard at his [113] peril, even in that case. When a more exact and specific rule has been arrived at, he must obey that rule at his peril to the same extent. But, further, if the law is wholly a standard of external conduct, a man must always comply with that standard at his peril.