The geometer's method of starting with definitions and axioms and proceeding from proposition to proposition especially appealed to Spinoza, apart from the fact that geometry was an ideal science, because, for Spinoza, the essence of logical method consists in starting out with ideas that are of utter simplicity. Then, if the ideas are understood at all, they can only be clearly and distinctly understood. The absolutely simple we can either know or not know. We cannot be confused about it. And ideas which are clearly and distinctly understood are, according to Spinoza, necessarily true. Such unambiguously simple and therefore necessarily true ideas Spinoza believed his definitions and axioms expressed. Furthermore, if we gradually build up the body of our science by means of our initial simple ideas, justifying ourselves at every step by adequate proof, our final result will necessarily be as firmly established and as certainly true as the elementary ideas we started with. The reliability of this whole procedure more than compensates for its tediousness--a defect Spinoza expressly recognizes. Unfortunately, however, there are other defects in the geometrical method when it is applied to philosophy, far more serious than its tediousness,--defects, moreover, Spinoza apparently did not recognize. Even though the geometrical method is preëminently scientific, it is hardly a form suitable for philosophy. The Euclidean geometer can take it for granted that the reader understands what a line or plane, a solid or an angle is. For formality, a curt definition is sufficient. But the philosopher's fundamental terms and ideas are precisely those in need of most careful and elaborate elucidation--something which cannot be given in a formal definition or axiom. Also, in the geometrical form, the burden of the author's attention is shifted from the clarification of the propositions to the accurate demonstration of them. Which, in a philosophical treatise, is most unfortunate. For though it is undoubtedly highly desirable that the philosopher should observe the same care and precision as the scientist, admitting nothing he cannot prove, it is nevertheless just as well for the philosopher to take reasonable care that what he is conscientiously proving is understood. That Spinoza did not always take such care but considerably over-estimated the self-evidence of his definitions and axioms and the simplicity of many of his important propositions, is an unhappy fact conclusively established by the increasing volume of Spinozistic literature. II