The belated English translation of Edith Stein’s Potenz und Akt comes as a welcome addition to the accessibility of Stein’s literary corpus at a time when the phenomenological method for philosophy continues to attract hopeful adherents. Originally written in 1931 as her application thesis for a position as lecturer at the University of Freiburg, Potenz und Akt was an attempt to synthesize the scholastic method of Thomas Aquinas and the phenomenological method of Edmund Husserl. Stein’s thesis was submitted to Husserl himself, as well as Martin Honecker and Martin Heidegger, for their review. While Stein’s goal of filling the position of lecturer at Freiburg remained unmet (largely due to economic constraints on the university), Stein continued to revise the manuscript in her attempt to articulate her personal philosophical vision which had 'found a home' in Thomistic thought. Potenz und Akt was first published in German by Herder in 1998.

Potency and Act could be classified as Stein’s most erudite, technical and creative work – even surpassing the prosaic style of her other prominent works such as Knowledge and Faith and Finite and Eternal Being. Potency and Act gives a systematic presentation of a philosophy of being based on the simple yet dynamic dialectic of potentiality and actuality. This work is divided into six primary sections: I. Issues of act and potency, II. Act and potency from the perspective of formal ontology, III. Transition from a formal to a material enquiry, IV. Attempt to define matter materially, V. Attempt to define spirit, and VI. Final things as hierarchy of ‘formed matter’ in contrast to Metaphysische Gespräche by H. Conrad-Martius, which includes a closing excursus on transcendental idealism. Stein convincingly shows how the dialectic of potentiality and actuality (so foundational for Thomistic thought) remains fundamental to philosophia perennis (‘perennial philosophy’) and an indispensable hermeneutic entry-point for philosophical anthropology.

Most striking about Stein’s work is her audacious way of vacillating (in Thomistic fashion) between treating the being of God, angels, human beings and other existents. In contrast to a thinker like Heidegger, Stein refuses to bracket her personal faith tradition or ‘theological’ concepts in treating the question of being. Rather, she unabashedly points to God (via analogia entis [‘through the analogy of being’]) as actus purus (‘pure act’) – as the sine qua non from whence all beings originate. Stein, like Thomas, contends that ‘actuality is prior to potentiality’ (cf. Summa contra gentiles, I.16.2) and that God is pure act, while creatures are always an admixture of potentiality and actuality. Stein is at pains to set forth a ‘genealogy of existence’ through an exhaustive taxonomic nomenclature, organizing beings according to genus, species, category, substance, individual, etc. Likewise, Stein maintains classic anthropological understandings, e.g. anima forma corporis (‘the soul is the form of the material body’), while proposing an inclusive notion of ‘spirit’ (Geist) as referring to not only a kind of metaphysical inner-self or divine life, but to ‘mind’ and the ‘specific essence of things’ as well.

Stein’s project is exemplar in how it subtly engages various ideological currents of modernity, e.g. materialism and atheism, by honestly grappling with the theory of evolution, amounting to a thoroughly public theo-anthropological proposal. Particularly fascinating is Stein’s expository dialogue with the thought of Hedwig Conrad-Martius – a dialogue that comprises the largest section of Stein’s book. In this section Stein openly takes issue with Conrad-Martius’ notion of a ‘soul of nature’ proceeding ‘from below’ in contradistinction to a ‘spiritualized soul’ reborn ‘from above.’ For Stein, all existence is graced and “bear(s) something of spirit in itself” (VI.4). Through the hermeneutic of potentiality and actuality, Stein is able to demonstrate the givenness of the pluriformity of existence – how material potentiality has given way to formal actuality through the symbiotic thoroughfare of creation, possible only via actus purus. In short, actuality cannot emerge from potentiality, just as something cannot emerge from nothing by the something’s own accord.

Finally, in Potency and Act, Stein unveils a holistic anthropology through a treatment of the various intrinsic dimensions of human personhood, e.g. understanding, insight, sense appetite, will, entelechy. However, one of Stein’s most profound insights is her treatment of grace at the end of her book. Stein characterizes grace as a ‘letting it happen’: “Only by God entering and ‘passing through’ – theology calls what enters ‘grace’ – is man ‘born of the spirit’ after having already been created by God as a personally spiritual be-ing [Wesen]” (VI.23.j). Stein sees freedom and ‘openness’ to grace as vitally constitutive of authentic humanity. The human person need simply keep herself free and open, acquiescing in an attitude of docility to the ‘awakening’ of divine life.

In conclusion, Potency and Act represents a paradigmatic instance of constructive philosophy and theology – a work that seeks to put voices new and old into conversation, resulting in ample fodder for continued reflection on and augmentation of philosophia perennis. Edith Stein demonstrates how when one "brings from her storehouse both the new and the old" (cf. Mt 13:52), a brilliant and unexpected fruitfulness obtains.