a different concert on the same day as the premiere of the Overture, his song Der Wanderer (D. 489) was performed. In 1822, Schubert made the acquaintance of both Weber and Beethoven, but little came of it in either case; however, Beethoven is said to have acknowledged the younger man's gifts on a few occasions. On his deathbed, Beethoven is said to have looked into some of the younger man's works and exclaimed: "Truly, the spark of divine genius resides in this Schubert!" Beethoven also reportedly predicted that Schubert "would make a great sensation in the world," and regretted that he had not been more familiar with him earlier; he wished to see his operas and works for piano, but his severe illness prevented him from doing so. Last years and masterworks Despite his preoccupation with the stage, and later with his official duties, Schubert wrote much music during these years. He completed the Mass in A-flat major, (D. 678) in 1822, and later that year embarked suddenly on a work which more decisively than almost any other in those years showed his maturing personal vision, the Symphony in B minor, known as the Unfinished Symphony (D. 759). The reason he left it unfinished – after writing two movements and sketches some way into a third – continues to be discussed and written about, and it is also remarkable that he did not mention it to any of his friends, even though, as Brian Newbould notes, he must have felt thrilled by what he was achieving. In 1823, Schubert wrote his first large-scale song cycle, Die schöne Müllerin (D. 795), setting poems by Wilhelm Müller. This series, together with the later cycle Winterreise (D. 911, also setting texts of Müller in 1827) is widely considered one of the pinnacles of Lieder. He also composed the song Du bist die Ruh' (You are rest and peace, D. 776) during this year. Also in that year, symptoms of syphilis first appeared. In 1824, he wrote the Variations in E minor for flute and piano; Trockne Blumen, a song from the cycle Die schöne Müllerin; and several string quartets. He also wrote the Sonata in A minor for arpeggione and piano (D. 821) at the time when there was a minor craze over that instrument. In the spring of that year, he wrote the Octet in F major (D. 803), a sketch for