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.

This chapter introduces the reader to how Theophrastus approaches the topic of plants by offering a selective discussion of the first book of History of Plants. This book is a prolegomenon to the study of plants. It is also a liminal space where Theophrastus negotiates the transition from the study of animals to the study of plants. From the very way Theophrastus refers to animals, we can infer that Theophrastus builds his whole edifice on the results achieved in the study of animals. This overall approach not only confirms that the Peripatetic study of perishable living beings is approached via separate studies of animals and plants but also suggests that the relevant order of study is first animals, then plants.