This volume applies a critical descriptive writing style to the text of William of Auvergne, bishop of Paris from 1228 to his death there in 1249. It can be read as a resourceful tool to navigate through the main themes of William's conception of science/natural philosophy. It is a coherent synthesis of Sannino's previous publications and of her 'long-lasting research' that has resulted in her authoritative expertise on William's writings. With this background, Sannino succeeds in highlighting the points of originality in William's thinking, such as his "rebuttal of astrological determinism" (60), his rejection of judicial astrology's attempt to interpret astral influence on the ordained course of nature, his opposition to idolatry, his preaching of the need for mathematics to understand a universe arranged by numbers, his treatment of marvels and magic, his belief in the curative use of music, and his aesthetic vision of the world understood as a harmonic universe where each part contributes to the final splendor of creation and reflects the beauty of the creator.

The book begins with an introductory chapter that sketches William of Auvergne's life and discusses the state of the art in modern scholarship on William's writings (7-30). Sannino's contribution to this literature on William is "a careful reconsideration of his texts" (28). She provides a new critical perspective that allows us to better understand William's indifference to Aristotelian natural philosophy, following his 'Augustinian background' and penchant for alternative sources, such as the Corpus Hermeticum or Avicenna's and Avicebron's writings.

The first chapter focuses on causation and deals with the combination of divine and astral causality. William's conception of the universe envisions the world as an aggregate of all beings acting around a first cause that generates everything. Sannino lucidly analyzes the notion of fatum (49) and its different meanings (predestination, prophecy, prediction, the chain of causes), to which William adds a new one by "constructing an etymology from the verb fari (to speak) and linking it to the word of God" (52).

His vision of causation is also explored in the second chapter, which investigates the two-way process of causation: from above to below and vice versa. William explains the influence of God on nature but also how nature interferes with divine causation. This is possible because God imbues the elements of nature with a vital power that can have a certain and evident impact: the curative effects of herbs or stones, the influence of the planets in determining future events in the life of a person, the virtues of talismans of various kinds, etc. Therefore, his effort to comprehend their action leads William to determine to what degree miracles or marvels should be considered an object of study, both by natural science and by theology. His investigation of natural magic is nourished by his reading of a wide range of sources from Aristotle to Arabic Hermeneutic texts. Looking to find examples of exotic phenomena, William introduces all kinds of interesting sources, such as the Liber vaccae (Liber Neumich, Kitab al-Nawams) used in De legibus (see 87-88) to demonstrate the impossibility of the artificial generation of life. This inspiring analysis explicates William's legacy and his impact on authors such as Nicole Oresme, who refers to this treatise in his De configurationibus qualitatum et motuum (ed. Clagett, II, 31, p. 358, ll. 60-68), as does Henry of Langenstein in his principium on the Sentences of Peter Lombard (Ms. Alençon, Bibliotheque municipale, 144, f. 6vb), later recycled in his treatise De reductione effectuum (Ms. Paris, BnF, lat. 14887, f. 85v). Both were extremely influenced by William's text, a heritage that deserves further attention.

From her investigation of William's sources, Sannino highlights William's increasingly deep hostility to idolatry (100-103) and his characterization of the "Hermetic texts as juvenile readings" (103). William admits that miracles are crucial for strengthening the Christian faith and serve as proof of God's intervention in the natural course of nature, as the examples in the Bible witness. At the same time, however, he sees the need to fortify the intellect and to reinforce the use of reason against superstition.

The third and final chapter (107-141) revolves around William's conception of the soul. William does not follow Aristotelian psychology but remains faithful to the Augustinian notion on the soul. For him, man is an imago Dei and the human soul should be understood as the border of the intellectual and physical realms (110). Following this vision, William introduces the idea that psychology is part of natural philosophy. Another aspect of his originality is that, under the influence of the Hermetic texts and also of the Liber de causis, he defines the soul as an incorporeal substance (115). In describing the soul's activity, William is particularly sensitive to the role played by music "to display philosophical values, more specifically, ethical balance and social moderation" (122). Aesthetical reflection on the effect of beauty is also at the heart of William's psychology, since he conceives the role of interior and exterior beauty in a theological perspective as a way of displaying God's beauty.

The legacy of William's ideas is explored in the conclusion of the book. A very useful census of his surviving manuscripts provides a measure of the circulation of his texts and reveals their impact on the development of scientific thinking across Europe into the fourteenth and fifteenth centuries. Color reproductions of details of the incipit of De universo in the University of Rochester manuscript are a delightful treat for the reader at the end of the book, just before an extremely lengthy bibliography (163-181). This volume of remarkable scholarship enriches the Micrologus collection.

Monica Brînzei