Cassiodorus Cassiodorus, Institutiones, 2, 5, 31 XI. Hyperdorius est lydium hemitonio, aeolium tono, phrygium tono semis, iastium duobus tonis, dorium duobus semis, hoc est diatessaron symphonia: hypolydium tribus tonis, hypoaeolium tribus semis tonis, hoc est diapente symphonia; hypophrygium quatuor tonis, hypoiastium quatuor semis, hypodorium quinque.