The good method does not precede knowledge, it comes from it. It is not prior, but internal to it. In other words, the method of reading follows from and from reading, so that the rules are given by Spinoza himself. To find it, one must then follow the first precept that Spinoza explicitly offers to his reader throughout all his correspondence. Each letter he addresses to his friends begins with the famous maxim "Caute" (Be cautious) that served as a seal and motto. Now, what is a slogan but an order, a rule that encompasses all the others and sums up, by its precision and conciseness, the thought of an author? That is why it is convenient first to elucidate the real philosophical significance of this privileged instrument that opens the doors of the system.