 Hume’s account of causality covers at least five related issues: (1) how we acquire an idea of cause; (2) what we mean by “cause;” (3) how we reason about causes; (4) whether causes are in the mind or in nature; (5) how we could infer the existence of causes. In this section, we explore how Hume’s treatment of what we mean by “cause” illustrates Hume’s critical response to and departure from Newton’s philosophy (see also Schliesser 2007). Hume’s treatment of causation straightforwardly rejects at least two kinds of causes that appear in Newton’s philosophy: final causes and simultaneous causes (Schliesser 2009). Moreover, we show that the structure of Humean causes is deeply indebted to the Pre-Newtonian mechanical philosophy associated with Boyle.