contain the word 'knowingly.'" (_2 Id. §172._)

As to a _presumed knowledge_ of the law, where the fact involves a
question of law, the same author says: "The general doctrine laid down
in the foregoing sections," (i.e. that every man is presumed to know the
law, and that ignorance of the law does not excuse,) "is plain in itself
and plain in its application. Still there are cases, the precise nature
and extent of which are not so obvious, wherein ignorance of the law
constitutes, in a sort of indirect way, not in itself a defence, but a
foundation on which another defence rests. Thus, if the guilt or
innocence of a prisoner, depends on the fact to be found by the jury, of
his having been or not, when he did the act, in some precise mental
condition, _which mental condition is the gist of the offence_, the jury
in determining this question of mental condition, _may_ take into
consideration his ignorance or misinformation in a matter of law. For
example, to constitute larceny, there must be an intent to steal, which
involves the knowledge that the property taken does not belong to the
taker; yet, if all the facts concerning the title are known to the
accused, and so the question is one merely of law whether the property
is his or not, still he may show, and the showing _will be a defence_ to
him against the criminal proceeding, that he _honestly believed it his
through a misapprehension of the law_."

(1 Cr. Law, §297.)

The conclusions of the writer here, are correct, but in a part of the
statement the learned author has thrown some obscurity over his own
principles. The doctrines elsewhere enunciated by him, show with great
clearness, that in such cases _the state of the mind constitutes the
essence of the offence_, and if the state of the mind which the law