Ave verum corpus Alt ernative. Title Composer Byrd, William: Opus/Catalogue Number Op./Cat. No. T 92 I-Catalogue Number I-Cat. No. IWB 12 Key G minor (?) First Pub lication. in Gradualia ac cantiones sacrae, Liber 1 (No) Librettist attr. Pope Innocent VI (/95–) Language Latin Average Duration Avg. Duration: 4 minutesComposer: Byrd, William. Ave Verum Corpus, performed here by the Tallis Scholars, is often regarded as the most popular piece William Byrd ever created. Byrd created the piece based on earlier versions of it dating all the way back to a 14th century poem by Pope Innocent IV. Ave Verum Corpus William Byrd () "Ave Verum" is considered by many to be William Byrd's finest work. It was first published in volume one of his Gradualia in Lyrics. The verse itself is from a 14th century handwritten document from Reichenau, penned by an unknown author. Translation. See my translation of Mozart's Ave Verum.