[...] I have no particular desire to influence you in your plans for an overture to Romeo & Juliet: but I should like to intimate what virtually amounts to a wish, namely that, before proceeding any further, you read an account of the Coriolanus Overture which I have written to assist our audience’s understanding of this work when it is next performed here, and which I shall send you as soon as it is printed. I was delighted to observe that this entire piece of music is no more and no less than the accompaniment to a graphic - almost mimic - scene between C. and his mother and wife in the camp outside Rome. You, too, should conflate the whole of the poem of R. & J. to produce a similar moment of graphic intensity: if you continue to plan the work along philosophical lines, your music can only become increasingly incomprehensible. For - once again - absolute music can express only feelings, passions and moods in their antitheses and degrees of intensity, but not relationships of a social or political nature. Beethoven has a splendid instinct for this: I almost prefer his poem of Coriolanus to Shakespeare’s, at least as regards its artistic conception, since it has a graphic unity and succinctness which almost allows the subject-matter to achieve the sensuality of myth.
[...]
Source: Selected Letters of Richard Wagner, trans. and ed. Stewart Spencer and Barry Millington (W. W. Norton & Company, 1988), No. 137