A major new concept of 17th-century natural philosophy was mechanical philosophy, an expressly anti-Aristotelian system that envisioned the world as a great machine functioning like a clockwork. Although the mechanical philosophy seemed to provide explanations of natural phenomena, it was not without problems—perhaps most crucially in its theologically unacceptable potential consequences. This lecture explores some versions of the mechanical philosophy in the work of Pierre Gassendi, René Descartes, Robert Boyle, and others.