To be human is to want to be better– if not a better person, then at least better at something. The first premise of this book is that we cannot strive to become better without some notion of the best; logically speaking, better implies best. The second premise is that the idea of the divine serves as the limit case of what is best in our practical reasoning; it is a conceptual truth about god that nothing better can be conceived. The third premise is that our ideas about the gods are an invaluable window on human nature. I then set out my principles for the interpretation of the Socratic philosophers and the Bible. Finally, I discuss the existing scholarship about “becoming like a god” in Greek philosophy and how I see this book in relation to it.

Both Socratic Greek philosophy and biblical religion endorse the human aspiration to become as much like a god or God as is humanly possible. This fact testifies to the important role that ideals of perfection play in human life. Against this fundamental similarity, however, important differences arise. First, in Socratic philosophy, deification rests on human not divine initiative. Socratic deification is primarily the product of rational self-discipline. The Bible, however, rejects as prideful this Greek ideal of self-deification. Biblical deification rests on divine not human initiative. Second, the gods of the Socratic philosophers are personifications of reason rather than divine persons. The gods of the philosophers are paradigms to be imitated rather than persons with whom we are in relationship. Third, the gods of the Socratic philosophers are cosmic gods whom we approach through the study of the orderly motion of the celestial bodies. By contrast, the biblical God is a divine person whom we approach through loving union with other persons, divine and human. Greek salvation takes us from here to there, from earth to heaven; biblical salvation takes us from now to then, from the present to the future.

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.

First, I argue that the aspiration to become like a god is an inescapable part of the human condition and is as common among atheists as among theists. I set aside the whole question of the existence of the gods and treat theology as a guide to anthropology. Ideas of the divine reveal essential truths about human beings. Second, I explore the ambivalence about this aspiration to divinity – an ambivalence found both in philosophy and in biblical religion. Third, I discuss the relation of philosophy to religion by showing that the great philosophers, especially the Socratic philosophers, have attempted to think through the presuppositions of religious thought. Fourth, I argue that common attempts to contrast Athens and Jerusalem as reason and faith are absurd. I show that the true differences between Greek philosophy and biblical religion emerge only against the background of the common project of attempting to become divine in both Athens and Jerusalem.

Socrates often said that he was merely a human being with no share in divine wisdom or virtue; but Socrates himself lived a life of superhuman self-control, wisdom, and virtue. There is an ironic contrast between his verbal professions of humility and the commanding power of his own heroic life. For example, despite his avowals of ignorance, Socrates also claimed to receive personal admonitions directly from the gods. My portrait of Socrates is based on the contrast between how he saw himself (in the Apology of Plato) and how he was viewed by his students (in Alcibiades’ memoir in Plato’s Symposium). Socrates presents himself as all-too-human, but his students saw him as quasi-divine. Despite his verbal modesty in the face of divine wisdom, Socrates’s own life and death became the very paradigm of how a human being can become godlike by means of rational discipline.

If any book could be said to condemn the whole idea of human beings attempting to become like God, then surely it is the Bible. At the very beginning of Genesis, a serpent (later identified as Satan) tempts Eve with the promise that, if she disobeys God by eating of the tree of the knowledge of good and evil, then she will be “as a god.” According to the Bible, the root of all evil is pride; and pride means precisely thinking that we could become divine. Jesus himself is condemned by the Jewish priests for the blasphemous arrogance of claiming to be divine. And yet, the Bible also promises the faithful that they can become “partakers of the divine nature.” What the Bible condemns, of course, is self-deification. If we surrender to God’s love and seek intimate relation to him, God promises to transform us into creatures who possess divine sanctity and everlasting life. The biblical God is less a paradigm of perfection that we might imitate and more a divine person with whom we might have a loving relationship. According to the Bible, we are divinized not by merely imitating God but by loving and being loved by him.

This chapter contains an outline of the book and of its main argument. It concentrates on the deep structure of the Peripatetic science of perishable living beings, which consists in separate but coordinated studies of animals and plants. It provides the reader with an initial idea of the contents of the book with an emphasis on the epistemic requirements that shape the Peripatetic study of perishable life.

The general theory of science outlined in Aristotle’s Posterior Analytics mandates that the scientific enterprise proceeds in stages, and that the two main stages of any scientific inquiry are the collection of the relevant data followed by their explanation – the pre-explanatory and the explanatory stages of inquiry, respectively. Aristotle’s study of animals illustrates this methodological insight in an especially clear way. Moreover, the following epistemic principle controls Aristotle’s study of animals: the study of animals must start from the most organized and most determinate form of life and must take that as its starting point to generate results that can be subsequently extended to what is comparatively less organized and less articulate. This means that the study of animals must begin with a discussion of the human body. This methodological insight is at work in Aristotle’s History of Animals. However, its significance goes well beyond the stage of the collection and presentation of the relevant data; this chapter shows that this rule of inquiry also shapes the explanation of the zoological data in Parts of Animals, Progression of Animals, and Generation of Animals. The chapter also discusses the distortions created by the application of this rule of inquiry with a concentration on Aristotle’s explanation of animal locomotion.

Theophrastus shares Aristotle’s methodological insight that the scientific inquiry unfolds in stages, and that the two main stages of any scientific inquiry are the collection of the relevant data followed by their explanation – the pre-explanatory and the explanatory stage of inquiry, respectively. This chapter shows that we should speak of two main stages of inquiry because the explanatory stage itself may unfold in various stages. In other words, the work that is required to arrive at an adequate (i.e., scientific) explanation may take place in steps and may require accomplishing different tasks. The chapter looks in some detail at how Theophrastus adopts this style of inquiry in his explanation of the various ways in which plants propagate.