unatoned for. Commonly a man cannot contemplate his duty, a difficult
or an unfulfilled duty especially, without a certain emotion, very
otherwise than as he views the axioms of mathematics. There is a great
difference emotionally, but intellectually the two sets of principles,
speculative and moral, are held alike as necessary truths, truths that
not only are, but must be, and cannot be otherwise: truths in which
the _predicate_ of the proposition that states them is contained under
the _subject_. Such are called _self-evident propositions_; and the
truths that they express, _necessary truths_. The enquiry into the
origin of our primary moral judgments is thus merged in the question,
how we attain to necessary truth.

6. The question belongs to Psychology, not to Ethics: but we will
treat it briefly for ethical purposes. And first for a clear notion of
the kind of judgments that we are investigating.

"The primary precepts of the law of nature stand to the practical
reason as the first principles of scientific demonstration do to the
speculative reason: for both sets of principles are self-evident. A
thing is said to be self-evident in two ways, either _in itself_, or
_in reference to us. _In itself_ every proposition, the predicate of
which can be got from consideration of the subject is said to be
self-evident. But it happens that to one who is ignorant of the
definition of the subject, such a proposition will not be
self-evident: as this proposition, _Man is a rational being_, is
self-evident in its own nature, because to name man is to name
something rational; and yet, to one ignorant what man is, this
proposition is not self-evident. And hence it is that, as Boethius
says: "there are some axioms self-evident to all alike." Of this
nature are all those propositions whose terms are known to all, as,