orms, that a person may rightfully be
compelled to fulfil it. Duty is a thing which may be _exacted_ from a
person, as one exacts a debt. Unless we think that it might be exacted
from him, we do not call it his duty. Reasons of prudence, or the
interest of other people, may militate against actually exacting it; but
the person himself, it is clearly understood, would not be entitled to
complain. There are other things, on the contrary, which we wish that
people should do, which we like or admire them for doing, perhaps
dislike or despise them for not doing, but yet admit that they are not
bound to do; it is not a case of moral obligation; we do not blame them,
that is, we do not think that they are proper objects of punishment. How
we come by these ideas of deserving and not deserving punishment, will
appear, perhaps, in the sequel; but I think there is no doubt that this
distinction lies at the bottom of the notions of right and wrong; that
we call any conduct wrong, or employ instead, some other term of dislike
or disparagement, according as we think that the person ought, or ought
not, to be punished for it; and we say that it would be right to do so
and so, or merely that it would be desirable or laudable, according as
we would wish to see the person whom it concerns, compelled or only
persuaded and exhorted, to act in that manner.[C]

This, therefore, being the characteristic difference which marks off,
not justice, but morality in general, from the remaining provinces of
Expediency and Worthiness; the character is still to be sought which
distinguishes justice from other branches of morality. Now it is known
that ethical writers divide moral duties into two classes, denoted by
the ill-chosen expressions, duties of perfect and of imperfect
obligation; the latter being those in which, though the act is
obligatory, the particular occasions of performing it are left to our
choice; as in the case of charity or beneficence, which we are indeed
bound to practise, but not towards any definite person, nor at any
prescribed time. In the more precise language of philosophic jurists,
duties of perfect obligation are those duties in virtue of which a
correlative right resides in some person or persons; duties of imperfect
obligation are those moral obligations which do not give birth to any
right. I think it will be found that this distinction exactly coincides
with that which exists between justice and the other obligations of