Indictment, in five counts, for manslaughter.
 
 The first count alleged that Franklin Pierce, at West Boylston, in the county of Worcester, "on the seventh day of January, in the year eighteen hundred and eighty-three, and on divers other days and times between that day and the ninth day of January, in said year eighteen hundred and eighty-three, in and upon one Mary A. Bemis of said West Boylston, in the county aforesaid, wilfully and feloniously, did make divers assaults, and that the said Franklin Pierce did then, and at the several times aforesaid, there wilfully, feloniously, ignorantly, rashly, injuriously, and improperly, put, pour, and place, and cause and procure to be put, poured, and placed, on and upon the body, arms, legs, and feet of her, the said Mary A. Bemis, certain large quantities, to wit, two gallons of kerosene oil, and that the said Franklin Pierce, by the means and in the manner aforesaid, did then, and at the several times aforesaid, there feloniously cause her, the said Mary A. Bemis, to be and become mortally sick, weak, shocked, diseased, and disordered in her body aforesaid, of which said mortal sickness, weakness, shock, disease, and  disorder of her body, occasioned and brought on by the means and in the manner aforesaid, from the said seventh day of January, in the year aforesaid, until the fourteenth day of said January, in the same year, at West Boylston aforesaid, in the county aforesaid, she, the said Mary A. Bemis, did languish and languishing did live, on which said fourteenth day of January, in the year aforesaid, at West Boylston aforesaid, in the county aforesaid, the said Mary A. Bemis, of the said mortal sickness, weakness, shock, disease, and disorder, occasioned and brought on as aforesaid, died. And so the jurors aforesaid, upon their oath aforesaid, do say that the said Franklin Pierce her the said Mary A. Bemis, in manner and form aforesaid, feloniously did kill and slay, against the peace of the said Commonwealth."
 
 The second count was as follows: "And the jurors aforesaid, on their oath aforesaid, do further present, that said Franklin Pierce, at said West Boylston, in the county aforesaid, on the seventh day of January, in the year eighteen hundred and eighty-three, and on divers other days and times between that day and the ninth day of January, in the year aforesaid, in and upon one Mary A. Bemis, of said West Boylston, in the county aforesaid, wilfully and feloniously, did make divers assaults, and that the said Franklin Pierce did then, and at the several times aforesaid, there wilfully, feloniously, ignorantly, rashly, injuriously, and improperly put, pour, and place, and cause and procure to be put, poured, and placed, in, upon, and through certain underclothing, to wit, certain drawers, undershirt, and stockings, certain large quantities, to wit, two gallons, of kerosene oil, and did then, and at the several times aforesaid, there and thereby, wet and saturate, and cause and procure to be wet and saturated, said underclothing, to wit, said drawers, undershirt, and stockings, with the said large quantities of kerosene oil, and did then, and at the several times aforesaid, there wilfully, feloniously, ignorantly, rashly, injuriously, and improperly, put and place, and cause and procure to be put and placed, on and upon the body, arms, legs, and feet, of her, the said Mary A. Bemis, said underclothing, to wit, said drawers, undershirt, and stockings, so wet and saturated with kerosene oil as aforesaid, and that the said Franklin Pierce did then, and at the several  times aforesaid, there wilfully, feloniously, ignorantly, rashly, injuriously, and improperly, cause and procure said underclothing, to wit, said drawers, undershirt, and stockings, so wet and saturated with kerosene oil as aforesaid, to remain on and upon the body, legs, arms, and feet of her, the said Mary A. Bemis, for divers long spaces of time, and that the said Franklin Pierce, by the means and in the manner aforesaid, did then and at the several times aforesaid, there feloniously cause her, the said Mary A. Bemis, to be and become mortally sick, weak, shocked, diseased, and disordered in her body aforesaid, of which said mortal sickness, weakness, shock, disease, and disorder of her body, occasioned and brought on by the means and in the manner aforesaid, from the said seventh day of January, in the year aforesaid, until the fourteenth day of said January, in the same year, at West Boylston aforesaid, in the county aforesaid, she, the said Mary A. Bemis, did languish and languishing did live, on which said fourteenth day of January, in the year aforesaid, at West Boylston aforesaid, in the county aforesaid, the said Mary A. Bemis, of the said mortal sickness, weakness, shock,   disease, and disorder, occasioned and brought on as aforesaid, died. And so the jurors aforesaid, on their oath aforesaid, do say that the said Franklin Pierce her, the said Mary A. Bemis, in manner and form aforesaid, feloniously did kill and slay, against the peace of said Commonwealth."
 
 The remaining counts differed but slightly from the preceding, and need not be set forth.
 
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OPINION:   [p. 174]   Holmes, J. The defendant has been found guilty of manslaughter, on evidence that he publicly practised as a physician, and, being called to attend a sick woman, caused her, with her consent, to be kept in flannels saturated with kerosene for three days, more or less, by reason of which she died. There was evidence that he had made similar applications with favorable results in other cases, but that in one the effect had been to blister and burn the flesh as in the present case.

   The main questions which have been argued before us are raised by the fifth and sixth rulings requested on behalf of the defendant, but refused by the court, and by the instructions given upon the same matter. The fifth request was, shortly, that the defendant must have "so much knowledge or probable information of the fatal tendency of the prescription that [the death] may be reasonably presumed by the jury to be the effect of obstinate, wilful rashness, and not of an honest intent and expectation to cure." The seventh request assumes the law to be as thus stated. The sixth request was as follows: "If the defendant made the prescription with an honest purpose and intent to cure the deceased, he is not guilty of this offence, however gross his ignorance of the quality and tendency of the remedy prescribed, or of the nature of the disease, or of both." The eleventh request was substantially similar, except that it was confined to this indictment.

   The court instructed the jury, that "it is not necessary to show an evil intent;" that, "if by gross and reckless negligence he caused the death, he is guilty of culpable homicide;" that "the question is whether the kerosene (if it was the cause of the death), either in its original application, renewal, or continuance, was applied as the result of foolhardy presumption or [p. 175] gross negligence on the part of the defendant;" and that the defendant was "to be tried by no other or higher standard of skill or learning than that which he necessarily assumed in treating her; that is, that he was able to do so without gross recklessness or foolhardy presumption in undertaking it." In other words, that the defendant's duty was not enhanced by any express or implied contract, but that he was bound at his peril to do no grossly reckless act when in the absence of any emergency or other exceptional circumstances he intermeddled with the person of another.

   The defendant relies on the case of Commonwealth v. Thompson, 6 Mass. 134, from which his fifth request is quoted in terms. His argument is based on another quotation from the same opinion: "To constitute manslaughter, the killing must have been a consequence of some unlawful act. Now, there is no law which prohibits any man from prescribing for a sick person with his consent, if he honestly intends to cure him by his prescription." This language is ambiguous, and we must begin by disposing of a doubt to which it might give rise. If it means that the killing must be the consequence of an act which is unlawful for independent reasons apart from its likelihood to kill, it is wrong. Such may once have been the law, but for a long time it has been just as fully, and latterly, we may add, much more willingly, recognized that a man may commit murder or manslaughter by doing otherwise lawful acts recklessly, as that he may by doing acts unlawful for independent reasons, from which death accidentally ensues. . . .

   But recklessness in a moral sense means a certain state of consciousness with reference to the consequences of one's acts. No matter whether defined as indifference to what those consequences may be, or as a failure to consider their nature or probability as fully as the party might and ought to have done, it is understood to depend on the actual condition of the individual's mind with regard to consequences, as distinguished from mere knowledge of present or past facts or circumstances from which some one or everybody else might be led to anticipate or   [p. 176]   apprehend them if the supposed act were done. We have to determine whether recklessness in this sense was necessary to make the defendant guilty of felonious homicide, or whether his acts are to be judged by the external standard of what would be morally reckless, under the circumstances known to him, in a man of reasonable prudence.

   More specifically, the questions raised by the foregoing requests and rulings are whether an actual good intent and the expectation of good results are an absolute justification of acts, however foolhardy they may be if judged by the external standard supposed, and whether the defendant's ignorance of the tendencies of kerosene administered as it was will excuse the administration of it.

   So far as civil liability is concerned, at least, it is very clear that what we have called the external standard would be applied, and that, if a man's conduct is such as would be reckless in a man of ordinary prudence, it is reckless in him. Unless he can bring himself within some broadly defined exception to general rules, the law deliberately leaves his idiosyncrasies out of account, and peremptorily assumes that he has as much capacity to judge and to foresee consequences as a man of ordinary prudence would have in the same situation. In the language of Tindal, C. J., "Instead, therefore, of saying that the liability for negligence should be coextensive with the judgment of each individual, which would be as variable as the length of the foot of each individual, we ought rather to adhere to the rule which requires in all cases a regard to caution such as a man of ordinary prudence would observe." Vaughan v. Menlove, 3 Bing. N. C. 468, 475; S. C. 4 Scott, 244.

   If this is the rule adopted in regard to the redistribution of losses, which sound policy allows to rest where they fall in the absence of a clear reason to the contrary, there would seem to be at least equal reason for adopting it in the criminal law, which has for its immediate object and task to establish a general standard, or at least general negative limits, of conduct for the community, in the interest of the safety of all.

   There is no denying, however, that Commonwealth v. Thompson, although possibly distinguishable from the present case upon the evidence, tends very strongly to limit criminal liability   [p. 177]   more narrowly than the instructions given. But it is to be observed, that the court did not intend to lay down any new law. They cited and meant to follow the statement of Lord Hale, 1 P. C. 429, to the effect "that if a physician, whether licensed or not, gives a person a potion, without any intent of doing him any bodily hurt, but with intent to cure, or prevent a disease, and, contrary to the expectation of the physician, it kills him, he is not guilty of murder or manslaughter." 6 Mass. 134, 141. If this portion of the charge to the jury is reported accurately, which seems uncertain, (6 Mass. 134) we think that the court fell into the mistake of taking Lord Hale too literally. Lord Hale himself admitted that other persons might make themselves liable by reckless conduct. 1 P. C. 472. We doubt if he meant to deny that a physician might do so, as well as any one else. He has not been so understood in later times.  Rex v. Long, 4 C. & P. 423, 436. Webb's case, 2 Lewin, 196, 211. His text is simply an abridgment of 4 Inst. 251. Lord Coke there cites the Mirror, c. 4, § 16, with seeming approval, in favor of the liability. The case cited by Hale does not deny it. Fitz. Abr. Corone, pl. 163. Another case of the same reign seems to recognize it. Y. B. 43 Ed. III. 33, pl. 38, where Thorp said that he had seen one M. indicted for killing a man whom he had undertaken to cure, by want of care. And a multitude of modern cases have settled the law accordingly in England. . . .

   If a physician is not less liable for reckless conduct than other people, it is clear, in the light of admitted principle and the later Massachusetts cases, that the recklessness of the criminal no   [p. 178]   less than that of the civil law must be tested by what we have called an external standard. In dealing with a man who has no special training, the question whether his act would be reckless in a man of ordinary prudence is evidently equivalent to an inquiry into the degree of danger which common experience shows to attend the act under the circumstances known to the actor. The only difference is, that the latter inquiry is still more obviously external to the estimate formed by the actor personally than the former. But it is familiar law that an act causing death may be murder, manslaughter, or misadventure, according to the degree of danger attending it. If the danger is very great, as in the case of an assault with a weapon found by the jury to be deadly, or an assault with hands and feet upon a woman known to be exhausted by illness, it is murder. Commonwealth v. Drew, 4 Mass. 391, 396. Commonwealth v. Fox, 7 Gray, 585. The doctrine is clearly stated in 1 East P. C. 262.

   The very meaning of the fiction of implied malice in such cases at common law was, that a man might have to answer with his life for consequences which he neither intended nor foresaw. To say that he was presumed to have intended them, is merely to adopt another fiction, and to disguise the truth. The truth was, that his failure or inability to predict them was immaterial, if, under the circumstances known to him, the court or jury, as the case might be, thought them obvious.

   As implied malice signifies the highest degree of danger, and makes the act murder; so, if the danger is less, but still not so remote that it can be disregarded, the act will be called reckless, and will be manslaughter, as in the case of an ordinary assault with feet and hands, or a weapon not deadly, upon a well person. . . . Or firing a pistol into the highway, when it does not amount to murder. . . . Or slinging a cask over the highway in a customary, but insufficient mode. . . . Or careless driving. . . .

   If the principle which has thus been established both for murder and manslaughter is adhered to, the defendant's intention   [p. 179]   to produce the opposite result from that which came to pass leaves him in the same position with regard to the present charge that he would have been in if he had had no intention at all in the matter. We think that the principle must be adhered to, where, as here, the assumption to act as a physician was uncalled for by any sudden emergency, and no exceptional circumstances are shown; and that we cannot recognize a privilege to do acts manifestly endangering human life, on the ground of good intentions alone.

   We have implied, however, in what we have said, and it is undoubtedly true, as a general proposition, that a man's liability for his acts is determined by their tendency under the circumstances known to him, and not by their tendency under all the circumstances actually affecting the result, whether known or unknown. And it may be asked why the dangerous character of kerosene, or "the fatal tendency of the prescription," as it was put in the fifth request, is not one of the circumstances the defendant's knowledge or ignorance of which might have a most important bearing on his guilt or innocence.

   But knowledge of the dangerous character of a thing is only the equivalent of foresight of the way in which it will act. We admit that, if the thing is generally supposed to be universally harmless, and only a specialist would foresee that in a given case it would do damage, a person who did not foresee it, and who had no warning, would not be held liable for the harm. If men were held answerable for everything they did which was dangerous in fact, they would be held for all their acts from which harm in fact ensued. The use of the thing must be dangerous according to common experience, at least to the extent that there is a manifest and appreciable chance of harm from what is done, in view either of the actor's knowledge or of his conscious ignorance. And therefore, again, if the danger is due to the specific tendencies of the individual thing, and is not characteristic of the class to which it belongs, which seems to have been the view of the common law with regard to bulls, for instance, a person to be made liable must have notice of some past experience, or, as is commonly said, "of the quality of his beast." 1 Hale P. C. 430. But if the dangers are characteristic of the class according to common experience, then he who   [p. 180]   uses an article of the class upon another cannot escape on the ground that he had less than the common experience. Common experience is necessary to the man of ordinary prudence, and a man who assumes to act as the defendant did must have it at his peril. When the jury are asked whether a stick of a certain size was a deadly weapon, they are not asked further whether the defendant knew that it was so. It is enough that he used and saw it such as it was. Commonwealth v. Drew, ubi supra. See also Commonwealth v. Webster, 5 Cush. 295, 306. So as to an assault and battery by the use of excessive force. Commonwealth v. Randall, 4 Gray, 36. So here. The defendant knew that he was using kerosene. The jury have found that it was applied as the result of foolhardy presumption or gross negligence, and that is enough.  Commonwealth v. Stratton, 114 Mass. 303, 305. Indeed, if the defendant had known the fatal tendency of the prescription, he would have been perilously near the line of murder. Regina v. Packard, C. & M. 236. It will not be necessary to invoke the authority of those exceptional decisions in which it has been held, with regard to knowledge of the circumstances, as distinguished from foresight of the consequences of an act, that, when certain of the circumstances were known, the party was bound at his peril to inquire as to the others, although not of a nature to be necessarily inferred from what were known. Commonwealth v. Hallett, 103 Mass. 452. Regina v. Prince, L. R. 2 C. C. 154. Commonwealth v. Farren, 9 Allen, 489.

   The remaining question[] may be disposed of more shortly. When the defendant applied kerosene to the person of the deceased in a way which the jury have found to have been reckless, or, in other words, seriously and unreasonably endangering life according to common experience, he did an act which his patient could not justify by her consent, and which therefore was an assault notwithstanding that consent. Commonwealth v. Collberg , 119 Mass. 350. See Commonwealth v. Mink, 123 Mass. 422, 425. . . .

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   Exceptions overruled.