[...] I am truly sorry not to have been able to find time to go into the matter of your Altgeige as thoroughly as I feel is necessary if I am to do my part to get this instrument the notice it demands. I am convinced that the general adoption of the Altgeige into our orchestras will for the first time do justice to the conceptions of composers who have been obliged to put up with the ordinary tenor violin when they really had in mind the tone of the Altgeige for their melody, and that, furthermore, it may bring about an important and very advantageous change in the whole handling of the string-quartet. The open A string of this no longer thin and nasal but clear and tuneful instrument will be able to take the place of the "stopped" A string of the violin in many a vigorous melody, as in their register the violins hitherto have impeded energetic proclamation of tone, so that Weber, for example, has very frequently been obliged to resort for strength to a wind-instrument, clarinet or oboe. The Altgeige will render this unnecessary in future and free the composer from the compulsion of using mixed colours when his conception is for strings alone. It is to be hoped now that this improved and very greatly ennobled instrument will be distributed to our best orchestras at once, and that the foremost viola players will be urgently recommended to cultivate it seriously. We must be prepared for great opposition in this matter as, unfortunately, the majority of our orchestral viola players are not exactly the flower of our string-instrumentalists. One stirring example, however, will bring us disciples, and in the end kapellmeisters and managers will have to lend encouragement. I very much regret that you brought your business to my notice so late in the day and that, moreover, I have been so very much in demand lately that I have been unable to do very assiduously even what might have been done in so short a time. Please give me news of the reception of your instrument by the excellent Herr Court-Musician Thoms of Munich. My friend Fleischhauer (Concert-Master at Meiningen) says he is ready to do what he can to recommend the use of the Altgeige at the approaching Dramatic Festival performances in Bayreuth. Consequently, I have the prospect of seeing at least two of these instruments used in my orchestra and am only sorry not to be able to employ six. [...]
Source: Letters of Richard Wagner, Vol. 2, selected and ed. Wilhelm Altmann, trans. M. M. Bozman (J. M. Dent & Sons, 1927), No. 685