ABSTRACT
If the demands of the Method largely determine the content of the Metaphysic, its rules determine its structure and form. The formal characteristics of the Metaphysic are very important for understanding it. In all branches of philosophy, it was the structure rather than the content of knowledge which appeared of importance to Descartes, since the first and chief requirement for reaching truth is that we should search for it in that orderly and methodical fashion of which we are told in the Regulae and in the Discourse on Method. Further, Regius is accused in the Preface to the Principles of having in his Fundamenta Physicae changed the necessary order of truth. The explanation of the criticism is that for Descartes the truth of ideas is a function of their order. Metaphysical truth must be demonstrated geometrically. But in the geometrical mode of writing two things must be distinguished, namely, the order and the method of proof.
