es nor extraordinaries of any one. It requires only
thoughtfulness and a good conscience. It requires only that a man fairly
and properly use the judgment he possesses, and the means he has of
learning his duty. It requires of him only the same care to know his
duty in regard to the law, that he is morally bound to use in other
matters of equal importance. _And this care it does require of him._ Any
ignorance of the law, therefore, that is unnecessary, or that arises
from indifference or disregard of one's duty, is no excuse. An accused
person, therefore, may be rightfully held responsible for such a
knowledge of the law as is common to men in general, having no greater
natural capacities than himself, and no greater opportunities for
learning the law. And he can rightfully be held to no greater knowledge
of the law than this. To hold him responsible for a greater knowledge of
the law than is common to mankind, when other things are equal, would be
gross injustice and cruelty. The mass of mankind can give but little of
their attention to acquiring a knowledge of the law. Their other duties
in life forbid it. Of course, they cannot investigate abstruse or
difficult questions. All that can rightfully be required of each of
them, then, is that he exercise such a candid and conscientious judgment
as it is common for mankind generally to exercise in such matters. If he
have done this, it would be monstrous to punish him criminally for his
errors; errors not of conscience, but only of judgment. It would also be
contrary to the first principles of a free government (that is, a
government formed by voluntary association) to punish men in such cases,
because it would be absurd to suppose that any man would voluntarily
assist to establish or support a government that would punish himself
for acts which he himself did not know to be crimes. But a man may
reasonably unite with his fellow-men to maintain a government to punish
those acts which he himself considers criminal, and may reasonably
acquiesce in his own liability to be punished for such acts. As those
are the only grounds on which any one can be supposed to render any
voluntary support to a government, it follows that a government formed
by voluntary association, and of course having no powers except such as
_all_ the associates have consented that it may have, can have no power
to punish a man for acts which he did not himself know to be criminal.

The safety of society, w