The fifth and final volume of Bolzano's letters to Fesl comprises 82 letters from the years 1846 to 1848, in which he tackles new projects despite his poor health, of which the writings on social issues - not least 'Über die Wohlthätigkeit' (1847) - appear during his lifetime, others, however, only appeared posthumously, including the 'Kurzgefaßte Lehrbuch der katholisch-christlichen Religion' (1849), the essay 'Ueber die Eintheilung der schönen Künste' (1849), 'Drei philosophische Abhandlungen []' (1851) and the 'Paradoxien des Unendlichen' (1851). In the last year of his life, Bolzano also took a clear stance on the political events known as the "bourgeois revolution".