Part II

Alone in Germany during winter, Descartes reflects that works built by one architect are more coherent than those assembled by many, and resolves to reform only his own beliefs.

Descartes warns that stripping oneself of all past beliefs is not safe for everyone, and that he applies this reform only to himself, never recommending it as a general project.

Descartes presents his four rules: accept nothing as true unless clearly known, divide difficulties into parts, proceed from simple to complex, and make complete enumerations.

Descartes applies his method to geometry and algebra, finding that combining their strengths lets him solve problems of remarkable difficulty and lays the groundwork for all sciences.

Descartes decides he is not yet ready to examine the foundations of philosophy and spends years exercising his method, eradicating errors, and gathering experience.