Maffie presents a detailed and comprehensive metaphysic to represent the complexities of Aztec (or more broadly Nahua) religious and philosophical thought at the time of the conquest. A philosopher trained in the Western tradition, Maffie draws on evidence that has been classified and interpreted primarily by historians, anthropologists, art historians, and historians of religion. His objective is to organize Aztec metaphysics in terms of concepts and metaphors centered and rooted in everyday life, although these are known almost entirely from surviving elite expressions and images.

Writing in a manner accessible to experts and non-experts, Maffie grapples with central tenets in Aztec cosmology such as teotl, ixiptla, and nepantla, which confounded Spanish colonizers and still challenge Western scholarship. His contribution is to probe their logical links to one another in order to model Aztec metaphysics as a systematic and internally coherent body of thought. The keys to Maffie's thesis, as the title indicates, are his insistence on a “process metaphysic” whereby all of reality is in flow, constantly emerging and forming in relation with other phenomena; a focus on teotl, often translated as god or sacred, and here understood as dynamic monistic power (force) that is coexistent with reality; the discrimination of three types of transformative movement (“motion-change”) of teotl; and the use of a weaving metaphor to capture the native logic of the continuous interlinking of cosmic forces and substances in an unending “becoming.”

Between a succinct introduction and a brief concluding reiteration of major ideas are eight substantive chapters organized by topic. The first three deal with familiar themes: teotl as power in motion and as cosmic process; Aztec religion as pantheistic rather than polytheistic; and agonistic inamic unity, whereby any force or influence is paired in a mutually constitutive yet mutually competitive way with a complement, such as male and female. This last is more often glossed as “complementary opposition” in Mesoamerican studies. The chapters are structured to form logical and empirical sets of arguments consisting of the author's thesis, a review of prior Aztec scholarship on the subject, comparisons to some similar constructs known from other world regions (not enough, in my opinion), intellectual objections to and implications of his interpretation, and the author's response to those objections. Some of his interpretations, such as pantheism, adhere to prior scholarship, which is exhaustively discussed; others are new and require further demonstration of their validity in the face of opposing opinions.

The three subsequent chapters explore the specific movements of teotl as a cosmic process of motion-change. They reconfigure prior scholarship that treated these elements as unrelated constructs: teotl as olin (pulsating motion), as malinalli (twisting motion that conveys energy), and as nepantla (reciprocal motion that binds inamic pairs). Maffie argues that nepantla is prior to other forms of cosmic motion and is foundational to Aztec metaphysics. Nepantla-motion accounts for the self-generation of teotl via the weaving metaphor; teotl is both the weaver of the cosmos and the product of that motion.

The following chapter links teotl's motion-change to the well known 260-day (tonalpohualli) and 365-day (xiuhpohualli) calendars and to the acosmogonic quality of Aztec metaphysics. The cosmos is always in process, neither starting nor stopping. Like other scholars, Maffie adopts the relationist view of time-place as a unitary phenomenon, but in his model it is the patterned unfolding of teotl as qualitatively different times and heterogeneous places weaving the cosmic fabric. These chapters are organized by the types of evidence presented: linguistic, literary, and graphic.

Many line drawings and photographs of Aztec objects, and designs from the painted books, are included to provide visual support for the author's interpretations. The penultimate chapter brings together all these constructs in a further delineation of the weaving metaphor, the constant orderly and transformative becoming of the cosmos that especially characterizes the current era, the Fifth Sun. Mesoamerican and other Native American scholars will find value in Maffie's arguments and compilation of evidence.