Is that solemn value a fact or fancy?
As far as proof and reason go, we can answer either way.

We have two simple and opposite statements set against each other, between which argument will give us no help in choosing, and between which the only arbiter is a judgment formed upon utterly alien grounds.

As for proof, the nature of the case does not admit of it.

The world of moral facts, if it existed a thousand times, could give no more proof of its existence than it does now.

If on other grounds we believe that it does exist, then signs, if not proofs of it, at once surround us everywhere.