A philosopher, astronomer, astrologer, and mathematician born c. 1100-1110 in Istria, Hermann of Carinthia is considered, along with Adelard of Bath, John of Seville, Gerard of Cremona, and Plato of Tivoli, one of the most important 12th-century translators of Arabic astronomical works. His most influential translation was Ptolemy's Planisphaerium (Toulouse, 1143), incorporating commentaries by Maslama al-Majriti, and his own major philosophical work De Essentiis (1143), organizing the cosmos around five Aristotelian categories. He also participated in Peter the Venerable's Quran translation project.