Note 85 — Chapter XXXVI
Reading edition
Plotinus had said, “Nothing that really is can ever perish” (οὐδὲν ἀπολεῖται τῶν ὄντων), as Dean Inge notes, The Philosophy of Plotinus, 1918, I, 189.
There is also resemblance between the Didascalicon (II, 13) and De eodem et diverso (p. 27, line 7) in their division of music into mundane, human, and instrumental. For this Boethius is very likely the common source.