The Holy Spirit and Moral Action in Thomas Aquinas is a detailed study of how, according to one of Christianity's greatest visionary thinkers, God's Holy Spirit is continuously at work in and through humanity's moral activity. Jack Mahoney, SJ, documents, notably from Aquinas's commentaries on scripture, how "the grace of the Holy Spirit" prompts and influences people's minds, as well as their decisions to act, occasionally in unexpected ways. Through the gift of connatural wisdom, the Spirit empowers humans to appreciate God's own wise and loving design for the whole of creation, and enables them to cooperate freely in fulfilling their unique part in it.

This book is a detailed study of how, according to Thomas Aquinas, God's Holy Spirit is continuously at work in and through humanity's moral activity. Jack Mahoney, SJ, documents from Aquinas's interpretation of scripture his portrait of the Holy Spirit in action, showing that for Aquinas, "the grace of the Holy Spirit" was a matter of the "prompting" or instigation (instinctus) of the Holy Spirit, who "drives" God's children in their decisions (Romans 8:14) and enlightens their minds through the "law of the Spirit of life" (Romans 8:2). Mahoney examines Aquinas's descriptions of various biblical characters responded in the Spirit to personal moral choices and dilemmas, sometimes in unexpected ways, and how the same can happen today, especially in the light of biblical and Aristotelian teaching on the flexible application of general moral rules in varying circumstances. He elaborates the three "constants" that serve for Aquinas as criteria for authenticating the Spirit's dynamic presence in people's moral activity. Finally, Mahoney shows that the overarching structure of Aquinas's thought on the Holy Spirit's role is the deployment in history of God's all-embracing wisdom, "ordering all things well" (Wisdom 8:1).