Antyllus' original writings were lost, but they were preserved by Oribasius (ca. 320–400) and Paul of Aegina (ca. 625–690), both of whom were Greek physicians as well as historians.[11] Galen clarified the anatomy of the trachea and was the first to demonstrate that the larynx generates the voice.[13][14] Galen may have understood the importance of artificial ventilation, because in one of his experiments he used bellows to inflate the lungs of a dead animal.[15][16]