In two independent writings, Thomas Aquinas (1224/25-1274) engages as a commentator with the late antique legacy of Boethius (480-524), specifically with his treatise on the Trinity and the so-called Hebdomad. The latter, which is also referred to as an axiom text due to its argumentative structure, serves as a foundational text of Neoplatonic ontology up until the 12th century and has been the subject of numerous commentaries. Following the onset of the reception of Aristotle, Thomas's interpretation in the 13th century stands out as a singular work independent of the already extinguished tradition of commentary. In the only complete commentary on a work of Boethius, Thomas discusses the raised question regarding the substantial goodness of the created. Based on a theological foundation of creation, he analyzes the concepts of being and good from logical and ontological perspectives. Through the innovative concept of participation, the relational determination of created being and divine origin made in his commentary is regarded as a reference text for the doctrine of participation.