Modern physics has abandoned the dominant early modern picture of material microstructure. The corpuscularian model of rigid, sharply defined chunks of completely solid material has been rejected in favour of a dynamical image: following Boscovich and Kant, we are now to think of the space-filling 'stuffing' of matter in terms of diffused fields of force that range in intensity and have fuzzy, interpenetrating borders. Physicists disagree over whether we should think of these space-filling fields as undergirded by a system of ontologically prior point particles, or whether we should think of the so-called particles as nothing more than focal concentrations or pulses propagated in fields. But in either case, I hope it is clear that the same basic framework of questions that plagued the early moderns still arises for the current conception of matter. Whether we think of a piece of matter as a cloud of point particles throwing out interlocking fields of force, or as a particle-free distribution of pure force across a region of space, either way we can still ask: how far forth can we rupture and separate the spatially distinct parts of this field (or fields, or fields-plus-particles)? Is this piece of matter finitely or infinitely divisible? Are the parts (smaller fields, or fields-plus-particles) into which it can be divided distinct beings, even prior to division? Or are they merely potential entities? Perhaps certain issues that faced the corpuscularian no longer arise—in particular, problems that presuppose sharp boundaries and immediate contact between rigid atoms. But the main questions that structure the early modern debate remain with us.
What are the philosophical morals of the early modern controversy over the internal architecture of material body? First, we should certainly thank the early moderns for focusing our minds on the problem. Barrow's talk of 'Labyrinths, Difficulties and Inconveniences', Boyle's fear of 'truths