Aquinas reads Boethius 1
This is of a page from a 1498 edition of the Opuscula of Thomas Aquinas, published in Venice (BMC V452; Goff T 257). This part of the volume contains the work Contra doctrinam retrahentium a religione and here, towards the end of ch. 7, Aquinas quotes Boethius: Natura enim, ut Boetius dicit, a perfectis sumit initium. Aquinas uses exactly the same phrase in the Summa Theologiae at IIaIIae 189.1 ad 5 and a very similar one at IIaIIae 1.7 (Sed natura semper initium sumit a perfectis ut Boetius dicit). At this second passage he cites the Consolatio Philosophiae as his source, Book 3 Pr. 10, although Aquinas appears to be paraphrasing rather than quoting precisely.
References: AQUINAS, Opuscula (Venice: Bonetus Locatellus, for Octavianus Scotus, 1498); AQUINAS, Summa Theologica, 6 vols (Rome: Ex Typographia Senatus, 1886); BOETHIUS, The Theological Tractates & The Consolation of Philosophy, Loeb Classical Library (London: Heinemann, 1918).