Ah! ah! friend Heckel! So your opinion changes so easily, does it? A little while ago you still advocated Unger—now you pin your faith to Jäger? Well, I am at it with Unger now. I have gone to great trouble to correct his Saxon vocalisation, which made his voice wholly unintelligible, but I believe now that I shall do better with him than with any other tenor known to me. I shall keep him here permanently, too. He was plainly a lost creature, though not lacking in energy. Jäger is excellent, but [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 677