Question: Who was the teacher of the composer of song The Shepherd On The Rock?

<P0-S0> Apollonius Cronus( fl. 4th century BCE) from Cyrene was a philosopher of the Megarian school. <P0-S1> Very little is known about him. <P0-S2> He was the pupil of Eubulides, and was the teacher of Diodorus Cronus, as Strabo relates: Apollonius Cronus, was from Cyrene, ... being the teacher of Diodorus the Dialectician, who also was given the appellation" Cronus," certain persons having transferred the epithet of the teacher to the pupil. <P0-S3> The epithet" Cronus" roughly translates as" old fogey". <SEP> <P1-S0> Peter Horton( born August 20, 1953) is an American actor and director. <P1-S1> He played Professor Gary Shepherd on the television series" Thirtysomething" from 1987 until 1991. <SEP> <P2-S0> "The Shepherd on the Rock" , D. 965, is a Lied for soprano, clarinet, and piano by Franz Schubert. <P2-S1> It was composed in 1828 during the final months of his life. <SEP> <P3-S0> Franz Peter Schubert (31 January 179719 November 1828) was an Austrian composer of the late Classical and early Romantic eras. <P3-S1> Despite his short lifetime, Schubert left behind a vast oeuvre, including more than 600 secular vocal works (mainly lieder), seven complete symphonies, sacred music, operas, incidental music and a large body of piano and chamber music. <P3-S2> His major works include the Piano Quintet in A major, D. 667 ("Trout Quintet"), the Symphony No. 8 in B minor, D. 759 ("Unfinished Symphony"), the ”Great” Symphony No. 9 in C major, D. 944, the three last piano sonatas (D. 958–960), the opera "Fierrabras" (D. 796), <P3-S3> the incidental music to the play "Rosamunde" (D. 797), and the song cycles "Die schöne Müllerin" (D. 795) and "Winterreise" (D. 911). <P3-S4> Born in the Himmelpfortgrund suburb of Vienna, Schubert's uncommon gifts for music were evident from an early age. <P3-S5> His father gave him his first violin lessons and his older brother gave him piano lessons, but Schubert soon exceeded their abilities. <P3-S6> In 1808, at the age of eleven, he became a pupil at the Stadtkonvikt school, where he became acquainted with the orchestral music of Haydn, Mozart, and Beethoven. <P3-S7> He left the Stadtkonvikt at the end of 1813, and returned home to live with his father, where he began studying to become a schoolteacher; despite this, he continued his studies in composition with Antonio Salieri and still composed prolifically. <P3-S8> In 1821, Schubert was granted admission to the Gesellschaft der Musikfreunde as a performing member, which helped establish his name among the Viennese citizenry. <P3-S9> He gave a concert of his own works to critical acclaim in March 1828, the only time he did so in his career. <P3-S10> He died eight months later at the age of 31, the cause officially attributed to typhoid fever, but believed by some historians to be syphilis. <P3-S11> Appreciation of Schubert's music while he was alive was limited to a relatively small circle of admirers in Vienna, but interest in his work increased significantly in the decades following his death. <P3-S12> Felix Mendelssohn, Robert Schumann, Franz Liszt, Johannes Brahms and other 19th-century composers discovered and championed his works. <P3-S13> Today, Schubert is ranked among the greatest composers of Western classical music and his music continues to be popular.