His works contain the earliest known formal study of logic, and were studied by medieval scholars such as Peter Abelard and Jean Buridan.
hɪz wˈɜːks kəntˈeɪn ðɪ ˈɜːlɪɪst nˈoʊn fˈɔːɹməl stˈʌdi ʌv lˈɑːdʒɪk, ænd wɜː stˈʌdid baɪ mˈɛdɪˌiːvəl skˈɑːlɚz sˈʌtʃ ɐz pˈiːɾɚɹ ˈeɪbəlˌɑːɹd ænd dʒˈiːn bˈɛɹɪdən.