We find these worries re-emerging at the start of the scientific revolution, as the mechanistic picture of the world inaugurated by Galileo, Descartes and Newton put the problem of the mind at center stage while paradoxically sweeping it under the rug. Galileo’s mathematisation of nature seemed to leave no space for the qualities we find in experience: the redness of the tomato, the spiciness of the paprika, the sweet smell of flowers. Galileo’s solution, in a move reminiscent of Democritus, was to strip matter of such sensory qualities. This led to the distinction between “primary qualities”—such as shape, size and motion—which were thought to really exist in matter, and “secondary qualities”—such as colours, odours and tastes—which were thought to exist only in the mind of the observer (or to exist as powers to cause ideas in the minds of observers).[3] Galileo and Descartes did not take the radical Democritian step of denying the existence of the secondary qualities; instead they placed them in the soul.[4] However, this of course led to a radical form of dualism, with a sharp metaphysical division between souls with their secondary qualities and bodies with their primary qualities.