Controversial cases of liability without fault involve the third postulate. Systematic writers have found no difficulty in reconciling the law of negligence with the will theory of liability and the doctrine of no liability without fault. Yet they must use the term fault in a strained sense in order to fit our law of negligence with its objective standard of due care, or the Roman cases of liability for _culpa_ judged by the abstract standard, into any theory of moral blameworthiness. The doctrine of liability for fault and for fault only has its roots in the stage of equity and natural law, when the moral and the legal are identified, and means that one shall respond for injuries due to morally blameworthy conduct upon his part. As Ames puts it, "the unmoral standard of acting at one's peril" is replaced by the question, "Was the act blameworthy?" But is an act blameworthy because the actor has a slow reaction time or was born impulsive or is naturally timid or is easily "rattled" and hence in an emergency does not come up to the standard of what a reasonably prudent man would do in such an emergency, as applied _ex post facto_ by twelve average men in the jury box? If our use of "culpable" here were not, as it were, Pickwickian, we should allow the defendant in such cases to show what sort of man nature had made him and to call for individualization with respect to his character and temperament as well as with respect to the circumstances under which he acted. As the Romanist would say, we should apply a concrete standard of _culpa_. But what the law is really regarding is not his culpable exercise of his will but the danger to the general security if he and his fellows act affirmatively without coming up to the standard imposed to maintain that security. If he acts, he must measure up to that standard at his peril of answering for injurious consequences. Whenever a case of negligence calls for sharp application of the objective standard, fault is as much a dogmatic fiction as is representation in the liability of the master for the torts of his servant. In each case the exigencies of the will theory lead us to cover up a liability irrespective of fault, imposed to maintain the general security, by a conclusive imputation of fault to one who may be morally blameless. This is no less true of cases where we speak of "negligence _per se_."