We have henceforth, therefore, only to observe the unwearied energy with which Brahms, during the succeeding years, added one work after another to the list of his compositions in each and every branch of serious music for the chamber and the concert-room: songs, vocal duets, choral works and instrumental solos accompanied and unaccompanied, concerted music for solo instruments, symphonies. The publications of the year 1877 were the Symphony and the four sets of Songs, Op. 69, 70, 71, 72, twenty-four songs in all, some of the texts of which are by Carl Candidus, Carl Lemke, Gottfried Keller, etc., and others imitations of folk-songs of various nationalities. Dr. Deiters says of them in his 'Johannes Brahms': 'As it seems to us, the composer identifies himself here more and more closely with classical form and achieves ever purer refinement of his material. Turn where one will (we mention for instance "Des Liebsten Schwur" from Op. 69) there can be no hesitation in counting these songs with the best to be found of their kind. Again we are constantly reminded of Franz Schubert, whose wealth of melody is revived, whilst in conciseness of construction, in conscious mastery of form, he is here greatly surpassed.' Heuberger gives a pleasant glimpse of Brahms co-operating in a festival performance arranged for December, 1877, by the Academic Choral Society of Vienna in honour of its distinguished honorary member, Billroth. Invited by Heuberger, Dr. Eyrich's successor as conductor of the society, to take part in the proceedings, the master at once promised to conduct two of his choruses, 'Ich schnell mein Horn' and 'Lied vom Herrn von Falkenstein,' as arranged for the occasion for men's voices by Heuberger, and, on his appearance at the last rehearsal to go through the well-prepared compositions, was greeted with a hurricane of welcome by the over two hundred students who formed the choir. At the festival performance next day 'Brahms joined in the students' songs as lustily as his rough, broken voice would permit. He had, as he told me, a very good soprano voice as a boy, but had spoilt it by singing too much during its mutation period.' Of another occasion, a party at Billroth's house, when choruses by Brahms and Goldmark were to be performed, Heuberger relates: 'By Brahms' suggestion I directed the preliminary practices which took place at the houses of some of his friends, the Osers and others. The day before the party Brahms and Goldmark came to the last rehearsal. The so-reputed cross-grained Brahms now conducted his "Marienlieder" and other works without much alteration of the nuances that I had practised. Goldmark, on the contrary, who was as much liked in private life as he was dreaded at rehearsal, studied indefatigably on and on.'[60]