Here is S. Thomas' commentary on Boethius' On the Trinity. It was written at Paris at the end of the 1250s. The work is divided into six questions, and three parts. Part I (questions 1 and 2) concerns human knowledge of God and the manifestation of divine truth. Part II (question 3) concerns the knowledge possessed by faith, and (question 4) the nature of numerical identity and difference and the causes of individuation. Part III (questions 5 and 6) concern the division and the methods of speculative science.
The work is unfinished, and sadly does not cover the difficult sections at the end of Part II of Boethius' essay, and none of part III. It is apparently one of the few texts in Thomas’ own writing .
Thomas' incipits are linked to Boethius text, also in the Logic Museum here.
Part 1 question 1 Concerning the knowledge of divine things
Part 1 question 2 Concerning the manifestation of knowledge of divine truth
Part 2 question 3 Concerning Those Things That Pertain to the Knowledge Possessed by Faith
Part 2 question 4 Concerning Those Things That Pertain to the Cause of Plurality
Part 3 question 5 The division of speculative science
Part 3 question 6 The methods of speculative science
 Saint Thomas Aquinas: the person and his work By Jean-Pierre Torrell
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