Aristotle’s theology is best understood in relation to Plato’s. Like Plato, Aristotle offers no science of god, but he does offer philosophers a way to immortalize themselves through the study and contemplation of the cosmos. First, Aristotle arrays all classes of substances, from the elements to the gods, in a single progressive hierarchy. Every substance in the cosmos, he says, strives to become as much like god as its own nature permits: each class of substance perfects itself by imitating the class above it. A person’s life, says Aristotle, develops through the classes of plants, animals, and humans—before striving to imitate the divine by contemplating the stars. We become like the god by climbing the ladder of classes of substances. Second, Aristotle’s god governs the cosmos not by managing it but purely by being an example of perfection—an example that magnetically draws all things toward him. The perfect happiness enjoyed by god inspires all other classes of substances to love and to imitate him. Similarly, a philosopher governs his household and his city not by managing them, but merely by the attractive power of the example he sets of godlike happiness.

Modern historians of science often discuss the twelfth-century “discovery of nature” as a milestone in our relations with the environment. This article explores medieval scientific, literary, and theological writers who contributed to this distinctive set of attitudes even as it documents the significant continuities between these writings and those of classical and late antique authorities on the natural world. It traces how the encyclopedic imagination provided a hierarchical framework for understanding the world, and how this ontological scaffolding, in turn, underpinned the twelfth-century revival of Neoplatonic thought, as medieval Christian writers would enthusiastically adopt an earlier tradition of personifying nature. In the thirteenth century, this magisterial Natura came to reflect advances in the “new” Aristotelian science that would become the foundation of the medieval university curriculum. While the synthesis of Christian Neoplatonism and Aristotelian physis would remain the predominant model of nature for several centuries, it also occasioned polemical debates over how God related to the universe that he created and how knowledge of the natural world was to be valued and instrumentalized. This medieval vision of a human-scaled, personified nature would prove philosophically durable up to the Scientific Revolution.

In this chapter I outline the transformation of systematics into phylogenetics by tracing the emergence of lineage thinking. One of the routes to a realist interpretation of the natural system of systematic relationships was to temporalize it. Lineage thinking emerged when the previously atemporal and symmetrical affinity relationships between contemporaneous taxa were replaced by asymmetrical ancestor-descendant relationships that tracked the arrow of time. This transition was accompanied by a rapid decrease in the diversity of shapes of affinity diagrams published in the systematic literature, and it marked a shift from predominantly reticulating or web-like systems to tree-like figures soon after the publication of Darwin’s On the origin of species in 1859. I argue that this graphic revolution largely records the influence of evolutionary expectations, as biologists redrew their diagrams to fit the theoretical dictates of Darwinian descent with modification. The current swell of enthusiasm for evolutionary networks has driven several recent authors to the peculiar argument that even Darwin disliked the tree of life as an evolutionary metaphor, an argument I will refute. Reconceiving the systematic relationships between taxa as phylogenetic pathways along which body plans evolve had an epistemic corollary. Speculation became a necessary tool for the evolutionary storyteller.

In this chapter I take a detailed look at the evolutionary storytelling of Ernst Haeckel. He founded phylogenetics as the science dedicated to tracing the evolution of lineages. Although Haeckel’s phylogenetic scenarios were nourished from a broad buffet of evidence, the biogenetic law was his favorite shortcut to create lineages of hypothetical ancestors, most famously the tiny cup-shaped Gastraea. A recent consensus has emerged that stigmatizes Haeckel’s phylogenies as unDarwinian constructs that are conceptually stained by teleological thinking and the linearity of the scala naturae. Instead, I argue that his trees are fully Darwinian, and that the linearity present in his trees and thinking is the linearity of evolving lineages that track the arrow of time. Lineage thinking was novel when Haeckel started writing, and his was marred by imperfections. It was up to the following generations of evolutionists to resolve the conceptual tension between the linear and branching aspects of evolution, a struggle that is still ongoing in today’s literature.

Biology and theology are interdependent theoretical sciences for Aristotle. In prominent discussions of the divine things (the stars and their unmoved movers) Aristotle appeals to the science of living things, and in prominent discussions of the nature of plants and animals Aristotle appeals to the nature of the divine. There is in fact a single continuous series of living things that includes gods, humans, animals, and plants, all of them living and, in a way, divine. Aristotle has this continuum of divine beings, and a theory of value that corresponds to it, in mind not only in key parts of his theology and natural science (including astrophysics and biology), but also in his practical philosophy. Here I can do little more than call attention to some important texts and attempt to offer a coherent account of them, without being able to enter into the usual interpretive disputes. I begin by clarifying the terms “theology” and “biology” and their place in Aristotle’s division of philosophy. Next, I discuss how Aristotle’s theology is informed by his biology, and then how his biology is informed by his theology. I end by discussing some implications of the interdependence of biology and theology for Aristotle’s ethics and exhortation to philosophy.

Philo’s interest in music is as known as it is overlooked in its philosophical implications. This chapter focuses on the importance of the musical paradigm in Philo’s thought and its relation to the other complementary model adopted by the philosopher: the pattern of the scala naturae, inherited from Stoicism. More specifically, Philo’s appeal to the notion of harmony introduces the idea of some orderly discontinuity in nature, implying both the transcendence of God and the limited condition of human rationality: the world is indeed governed by harmony, but only in the very qualified sense that it implies harmonically defined relationships between very distant entities. This ‘vertical’ harmony, however, is combined with a ‘horizontal’ one, for God also exerts his providence through harmony, while, in turn, music is the intellectual means by which man can contemplate the heavens and draw closer to God. These are not mere metaphors, for music represents a proper philosophical model for Philo that he applies to aspects which will prove fundamental in the post-Hellenistic age.