Summary of Part Two of the Discourse on Method (René Descartes) In this part, Descartes explains how he decided to reject everything he had previously learned, as he saw that many of his beliefs were dubious or shaky. He explains that true knowledge cannot be built on unstable foundations, so he sets out to find a clear and secure method for reaching the truth. To this end, he presents four fundamental rules of his method, which are: 1. Evidence: Never accept anything as true unless it is clearly and distinctly known, that is, avoid hasty judgments and prejudices. 2. Analysis: Divide each problem into as many parts as possible to better resolve it. 3. Synthesis: Guide thoughts from the simplest to the most complex elements. 4. Revision: Make such complete accounts and such general revisions that you are sure nothing is omitted. He also recounts how he first put this method into practice, isolating himself from the world and devoting himself to observing his own reason, in order to arrive at purer conclusions. It was then that he became convinced that he could build true knowledge based on firm rules.