was an element, though not the chief element, of punishment.

[46] But, again, the supposed intuition of fitness does not seem
to me to be coextensive with the thing to be accounted for. The
lesser punishments are just as fit for the lesser crimes as the
greater for the greater. The demand that crime should be followed
by its punishment should therefore be equal and absolute in both.
Again, a malum prohibitum is just as much a crime as a malum in
se. If there is any general ground for punishment, it must apply
to one case as much as to the other. But it will hardly be said
that, if the wrong in the case just supposed consisted of a
breach of the revenue laws, and the government had been
indemnified for the loss, we should feel any internal necessity
that a man who had thoroughly repented of his wrong should be
punished for it, except on the ground that his act was known to
others. If it was known, the law would have to verify its threats
in order that others might believe and tremble. But if the fact
was a secret between the sovereign and the subject, the
sovereign, if wholly free from passion, would undoubtedly see
that punishment in such a case was wholly without justification.

On the other hand, there can be no case in which the law-maker
makes certain conduct criminal without his thereby showing a wish
and purpose to prevent that conduct. Prevention would accordingly
seem to be the chief and only universal purpose of punishment.
The law threatens certain pains if you do certain things,
intending thereby to give you a new motive for not doing them. If
you persist in doing them, it has to inflict the pains in order
that its threats may continue to be believed.