Peter Helias (Petrus Helias) (c. 1100 – after 1166) was a medieval priest and philosopher. Born in Poitiers, he became a pupil of Thierry of Chartres at Paris in the 1130s, also teaching grammar and rhetoric in his school. Around 1155 he returned to Poitiers where he later died.[1]
Other influences beside Thierry include William of Conches. He contributed to the theory of substance, and through Thierry, is meant to have been influenced particularly by Boethius.
In linguistics, he is regarded as having contributed ideas key to the development of grammatical categories such as parts of speech.