De processione Spiritus Sancti

Nilus Cabasilas's De processione Spiritus Sancti is a significant work in Greek Orthodox theology, focusing on the procession of the Holy Spirit. This treatise presents the Orthodox speculative view of the Trinity, emphasizing the Holy Spirit's origin from the Father alone. Cabasilas rejected the Western theological position, particularly as articulated by Thomas Aquinas, which posited that the Holy Spirit proceeds from both the Father and the Son (the Filioque clause). Consequently, De processione Spiritus Sancti became a foundational text for Eastern Orthodox apologetics. The work also reflects Cabasilas's support for Greek monastic spirituality and his engagement with the theological debates of his time.12