The Diva's Ruby by F. Marion Crawford

Mr. Van Torp knew no more about Bayreuth than about Samarkand, beyond the fact that at certain stated times performances of Wagner's operas were given there with as much solemnity as great religious festivals, and that musical people spoke of the Bayreuth season in a curiously reverent manner. He would have been much surprised if any one had told him that he often whistled fragments of _Parsifal_ to himself and liked the sound of them; for he had a natural ear and a good memory, and had whistled remarkably well when he was a boy.

The truth about this seemingly impossible circumstance was really very simple. In what he called his cow-punching days, he had been for six months in company with two young men who used to whistle softly together by the hour beside the camp fire, and none of the other 'boys' had ever heard the strange tunes they seemed to like best, but Van Torp had caught and remembered many fragments, almost unconsciously, and he whistled them to himself because they gave him a sensation which no 'real music' ever did. Extraordinary natures, like his, are often endowed with unnoticed gifts and tastes quite unlike those of most people. No one knew anything about the young men who whistled Wagner; the 'Lost Legion' hides many secrets, and the two were not popular with the rest, though they knew their business and did their work fairly well.