ABSTRACT
The operation of Meteors VIII renders simple and knowable what is, at first, complex and unknowable. But the knowable simples are plural. For them to be understandable, for them to form a science, they must be arranged into some sort of structure and their interrelations must be made perspicuous. This is what is involved in the application of the fourth precept. The structure Descartes has in mind is set out in the well-known simile of the tree of knowledge in the ‘Letter-Preface’ to the French edition of the Principles.
