Herman of Carinthia translates Claudius Ptolemy's significant work, Planisphaerium, producing it in Toulouse in 1143 from an Arabic translation from the Greek (jointly with commentaries of Maslamah Ibn Ahmad al-Majriti, who worked in Córdoba in the tenth century).

Western European scholastics became aware of Ptolemy's astronomical views via this translation dedicated to Thierry of Chartres. (This translation will for a long time be believed to be the only surviving link to Ptolemy's original. Later, another Arabic translation will be found to have been preserved in Istanbul).

Herman also translates Ptolemy's Canon (Canon of Kings).

For a long time, many will think that Ptolemy had been translated by the German Herman Contractus and not by Herman of Carinthia.

Herman’s original contribution to philosophy is De essentiis ("On essences").

In this work Herman deals with five Aristotelian categories (causa, motus, spatium, tempus, habitudo).

He starts to write this treatise in 1143 in Toulouse and he completes it the same year in Béziers.