Descartes identifies withdrawal of the mind from the senses as one of the greatest benefits of the First Meditation doubt. This paper develops an account of how withdrawal from the senses serves Descartes’s goal of using the Meditations to lay the foundations for his mechanistic physics. The account emphasises the role of the Second Meditation in the process of withdrawal, and locates Descartes’s attack on the naïve-cum-Aristotelian view of the senses in the Third Meditation, rather than in the First. In contrast to the view that Descartes is concerned to withdraw sensible qualities from the physical world, I argue that the main goal of his anti-Aristotelian, pro-physics campaign is to persuade the meditator of his anti-Aristotelian account of the way in which the senses and the intellect contribute to knowledge of the physical world.