nes ▁Sor el ▁by ▁Ad al bert ▁Gy row etz . ▁ ▁Life ▁S onn le ith ner ▁began ▁working ▁for ▁the ▁V ienn ese ▁court ▁in ▁ 1 7 8 7 , ▁first ▁at ▁Joseph ▁II ' s ▁private ▁office ▁and ▁later ▁in ▁the ▁ch an cell ery . ▁From ▁ 1 7 9 6 ▁he ▁published ▁the ▁Wiener ▁Theater - Al man ach , ▁and ▁in ▁ 1 8 0 2 ▁he ▁became ▁partner ▁in ▁the ▁Kunst ▁und ▁Indust rie - Com pt oir ▁publishing ▁house . ▁For ▁a ▁short ▁period ▁from ▁February ▁to ▁August ▁ 1 8 0 4 ▁he ▁served ▁as ▁art istic ▁director ▁of ▁the ▁Theater ▁an ▁der ▁Wien , ▁and ▁from ▁ 1 8 0 4 ▁to ▁ 1 8 1 4 ▁as ▁secretary ▁of ▁court ▁the aters ▁in ▁Vienna . ▁He ▁was ▁also ▁a ▁leading ▁figure ▁in ▁V ienn ese ▁musical ▁life ▁in ▁the ▁first ▁dec ades ▁of ▁the ▁nin ete enth ▁century ▁and ▁consequ ently ▁one ▁of ▁the ▁found ers ▁of ▁the ▁Gesellschaft ▁der ▁Musik fre unde , ▁serving ▁as ▁its ▁first ▁secretary ▁starting ▁in ▁ 1 8 1 2 . ▁ ▁S onn le ith ner ▁was ▁one ▁of ▁the ▁earliest ▁collect ors ▁of ▁fol ks ongs ▁and ▁information ▁on ▁their ▁compos ers ▁in ▁Austria , ▁a ▁project ▁which , ▁though ▁never ▁ful filled , ▁formed ▁the ▁basis ▁of ▁a ▁new ▁musical ▁en cyc lopedia . ▁He , ▁his ▁nep hew ▁Gr ill par zer ▁and ▁Franz ▁Sch ub ert ▁were ▁close ▁friends .