As noted at the end of chapter 1, a theme of the mature Leibniz's metaphysic conspicuously absent from the Disputatio is the identity of persisting individual substances over time. We develop that theme in the current chapter, indicating how its treatment in the hands of Leibniz is distinctive in comparison with both scholastic and contemporary approaches. In this context we can deliver on some promissory notes of previous chapters about the nature of individual substances themselves.

Scholastic philosophers gave no privileged place in their accounts of individuation to what contemporary metaphysicians have invented as something of a pastime – the topic of diachronic identity. This is not to deny that at some level the scholastics had views about the diachronic aspects of substances: in particular, substances endure through time despite a change of accidents. Accounts of what constitutes a substance's persisting over time, meanwhile, were wrung from a much broader range of considerations than one finds in contemporary approaches to diachronic concerns about substances. Of special import for the scholastic turn of mind were kinds of change in addition to change of accident. In particular, two other sorts of change, very much at the metaphysical groundfloor, demanded attention: (i) Aristotelian generation and corruption, whereby substances arise and dissipate in the natural world, and (ii) ex nihilo creation and annihilation. In investigating (i) and (ii) scholastic metaphysicians found pressure towards a component ontology of individual substance – to what we called in chapter 1 a “blueprint approach” to individuation.