Madonna was an early Italian (medieval) word for a noble or otherwise important woman (it survived only in the previous sense), and is widely used in art, especially by Renaissancepainters (see Mona Lisa.)
... to the doctrines of Hegel and Schleiermacher. After holding the chair of philosophy at Halle for two years, he became, in 1833, professor at the university of Königsberg[?], ...