 Already at an early time Bolzano came to be surrounded by a circle of friends and pupils who spread his thoughts about and stayed connected with their teacher, in spite of all reprisals. Michael Josef Fesl (1788–1864) and Franz Příhonský (1788–1859) were Bolzano’s closest collaborators in many cases and responsible for the edition of his writings (which Bolzano could not himself publish due to the ban of publication hanging over his head). They wrote in addition various works (introductions to editions of works, reviews and discussions of books, and replies to unfavorable reviews), for which Bolzano himself often provided the outline. Only Robert Zimmermann (1824–1898), whom Bolzano had privately taught philosophy and mathematics, had a career as a professional philosopher. In 1859 he was called, under Minister Thun, to the philosophical chair of the University of Vienna, which he took up in 1861. (Franz Brentano became his colleague there.) Zimmermann was, however, mainly concerned with aesthetics and turned more and more away from Bolzano’s philosophy to Herbart’s. 