He is therefore bound to draw that inference, or, in other words,
is chargeable with knowledge of that fact also, whether he draws
the inference or not. If then, he throws down a heavy beam into
the street, he does an act [56] which a person of ordinary
prudence would foresee is likely to cause death, or grievous
bodily harm, and he is dealt with as if he foresaw it, whether he
does so in fact or not. If a death is caused by the act, he is
guilty of murder. /1/ But if the workman has reasonable cause to
believe that the space below is a private yard from which every
one is excluded, and which is used as a rubbish heap, his act is
not blameworthy, and the homicide is a mere misadventure.

To make an act which causes death murder, then, the actor ought,
on principle, to know, or have notice of the facts which make the
act dangerous. There are certain exceptions to this principle
which will be stated presently, but they have less application to
murder than to some smaller statutory crimes. The general rule
prevails for the most part in murder.

But furthermore, on the same principle, the danger which in fact
exists under the known circumstances ought to be of a class which
a man of reasonable prudence could foresee. Ignorance of a fact
and inability to foresee a consequence have the same effect on
blameworthiness. If a consequence cannot be foreseen, it cannot
be avoided. But there is this practical difference, that whereas,
in most cases, the question of knowledge is a question of the
actual condition of the defendant's consciousness, the question
of what he might have foreseen is determined by the standard of
the prudent man, that is, by general experience. For it is to be
remembered that the object of the law is to prevent human life