"We proceed to offer some observations and illustrations, with a view to show that in the ordinary case where death is occasioned by the doing an act attended with manifest peril to life, the conclusion is properly not one of law but of fact, and that it is for the jury to decide whether the offender wilfully exposed life to manifest peril. Upon their affirming or negativing this proposition, the question whether he be guilty or not of murder, ought, we think, to depend. The 'mens mala', - the heart regardless of social duty, - are figurative expressions used to denote the criminal apathy or indifference with which an act is wilfully done which puts human life in peril. Whether such a peril be wilfully occasioned is a question not of law but of fact, depending on a consideration of the nature of the act done, the circumstances under which it was done, the probability that the act under those circumstances would be fatal to life, and the consciousness on the part of the offender that such peril would ensue. If A, knowing that one of two pistols was loaded with ball, but without knowing which, took one, and applying the muzzle to the head of B, pulled the trigger and shot him, having by chance taken the loaded one, this would be murder; for A wilfully placed B's life in peril by his act. Here it was an even chance whether B was killed or not, - but it is evidence that the principle and the law founded upon it must be the same, even although the probability were less; as for instance, though the selection were made from three or four (one only being loaded) instead of two; although no doubt the degree of probability may be an important circumstance in ascertaining the fact of the intention of the offender to put in danger. Neither the nature nor the degree of peril can possibly be the subject of legal definition; as well the knowledge of the offender that such peril exists, as the wilfulness of his act in proceeding notwithstanding that knowledge, are necessarily matters of fact, the existence of which is for the consideration of the jury. It may no doubt frequently appear, from the particular facts found by the jury, that the offender did wilfully expose human life to manifest peril, but still, as in numerous instances the court may be unable to draw the conclusion from the mere facts, it seems to be clear, as a general position, that the question is one of fact for the jury. In particular, it may be noticed that the fact of knowledge on the part of the accused, of the peril he was about to occasion by his act, must very frequently depend upon mere circumstantial evidence, upon the effect of which it is the province of a jury to decide. Malice, in the legal sense of the word, means, according to Mr Justice Foster, the mala mens, the heart bent upon mischief, as evidenced by general symptoms and circumstances. When this definition is applied to an ordinary case of implied malice, as where a man throws a heavy stone over a wall into a street, through which many persons are likely to be passing, malice thus defined assumes a more precise meaning. The offender in such case does not intend the death or hurt of any one in particular, - the act may kill a stranger or may do no hurt at all: there is nothing, therefore, to make it criminal, and so to constitute implied malice, but the peril of destroying life wilfully occasioned. The 'heart bent on mischief' must in this case, and it is apprehended in all others, in the absence of a special definite rule of law which defines what is meant by implied malice, consist simply in the disregard of life manifested by exposing life to peril, although no malice in the popular sense of the term exist against any individual. It is the wilful exposure of life to peril that constitutes the crime. If one, knowing cakes to contain deadly poison, were to scatter them in a public street, and death were the consequence, the act would be murder, for the offender knew that what he did was likely to occasion loss of life; but if one did the same act without knowing or suspecting that the cakes contained poison he would be innocent in law as well as in morals, for, although the act be in truth equally dangerous whether knowledge exist or not, in the one case great peril to life is wilfully occasioned, and in the other not. And so in all cases it is essential to the criminality of the act, both in law and morals, not only that the act should in its own nature under the circumstances be attended with peril to life, but that the offender should be aware of such peril. Where the offender does an act attended with manifest danger to life wilfully, that is with knowledge of the consequences, he may properly be said to have the 'mens mala, or heart bent upon mischief'; but if he does an act, however dangerous it be in its own nature, without any knowledge or suspicion of its tendency, that is, if he does not wilfully place life in peril, he cannot be said to show the mens mala, or heart bent on mischief. In such cases, therefore, it is plain that implied malice in law, according to Mr Justice Foster's notion, means nothing more than the state or disposition of the offender's mind when he wilfully does an act likely to kill or wilfully intends to put life in peril; but this is a conclusion to be drawn from the facts, viz., the probability that death will result from the act under the particular circumstances of the case, and the intention of the offender to occasion the peril regardless of consequences. ... In so atrocious a case as that of scattering poison, above, supposed, no doubt could well be entertained as to the guilt of the offender, dependent as it is on the circumstances of the act being in its own nature attended with manifest peril to life, and of the criminal intention on the part of the offender wilfully to place life in peril. In other instances, although the evidence be not so cogent, it will be found that the difficulties arise not from the necessity of calling in aid the operation of any new principle, or the applicability of those adverted to, but merely from doubt arising upon the matter of fact. The degree of probability that death will ensue from the act is susceptible of every variety from moral certainty to the remotest possibility; - the intention of the actor is also capable of degrees, closely indeed dependent on the greater or less degree of probability of mischief, from a direct intention to destroy life, to perfect innocence. And such varieties, it may be observed, are not merely in proportion to the risk, but depend also on the knowledge and consciousness of the risk to life. These elements are obviously matters of fact, to be decided as facts; they are beyond the reach of definition, and when probability of loss of life from doing the act, the knowledge of that probability on the part of the offender, and his criminal intention to occasion the risk have been determined in fact, the principle of law applies. It is upon these principles that the different degrees of legal guilt, in the absence of a direct intention to kill, depend. If poison instead of being, as in the case above supposed, used in such a manner as to occasion manifest danger to life, and with consciousness and knowledge of such danger, were to be used for the destruction of rats by placing it in a closet locked for greater precaution, the loss of human life would still be a barely possible, although most improbable, result from the act; a thief might by possibility break open the closet, and mistaking the poison for food, eat it and die. Here the fatal result would occur without the least blame, legal or moral, on the part of him who thus laid the poison. But between these two extreme cases lie an infinity of others, in respect of which important legal distinctions are requisite, although they may vary almost imperceptibly from each other, and particularly as to the degree of risk to human life which may be incurred. ... [T]he question is properly one of fact, as dependent on the existence of peril, and the design to expose to peril."