Faith In A Reference

It is tactful, when making an obscure reference, to arrange that the verse shall be intelligible even when the reference is not understood.  Thus many conceits are prepared to be treated as subdued conceits, though in themselves they have been fully worked out.  Consider as the simplest kind of example

The brotherless Heliades
Melt in such amber tears as these.

(Marvell, The Nymph Complaining.)

If you have forgotten, as I had myself, who their brother was, and look it up, the poetry will scarcely seem more beautiful; such of the myth as is wanted is implied.  It is for reasons of this sort that poetry has so much equilibrium, and is so much less dependent on notes than one would suppose.  But something has happened after you have looked up the Heliades; the couplet has been justified.  Marvell has claimed to make a classical reference and it has turned out to be all right; this is of importance, because it was only because you had faith in Marvell’s classical references that you felt as you did, that this mode of admiring nature seemed witty, sensitive, and cultured.  If you had expected, or if you had discovered, that Marvell had made the myth up, the couplet might still be admired but the situation would be different; for instance, you would want the brother to be more relevant to the matter at hand.

--William Empson, Seven Types of Ambiguity