All 9 chapters — from the letter to the Sorbonne through the six meditations.
The Meditations has three prefatory texts and six meditations. The Letter of Dedication and Preface explain the project's purpose and address early objections. The Synopsis maps the argument before it begins. The six meditations run over six imagined days: doubt (Meditation 1), recovery of the self (II), proof of God from the idea of God (III), the source of error (IV), the ontological proof (V), and the existence of bodies and the real distinction of mind and body (VI). Read them in order, slowly, the first time through.
The dedication, the preface, and the roadmap.
Descartes addresses the theologians of the Sorbonne, explaining that he intends to prove by natural reason that God exists and that the soul is distinct from the body — and asking, very carefully, for their protection.
Descartes addresses the reader directly and answers in advance the two main objections raised against his 1637 sketch of the argument — about whether the mind is exclusively a thinking thing, and whether an idea of perfection proves its object exists.
A six-paragraph map of the entire argument. Descartes describes what each meditation establishes — and notes, with characteristic precision, what the book does not claim to prove, including the immortality of the soul.
Doubt everything; find the one thing that survives.
The great demolition. Descartes takes apart his beliefs layer by layer — the senses, then dreaming, then the evil deceiver — until nothing is left standing. Methodic doubt reaches its maximum extent.
The cogito and the wax example. In the wreckage of total doubt, Descartes finds that the thinking, doubting self cannot be doubted — and then shows, through the famous wax argument, that the mind is more directly known than any physical object.
Two proofs of God; the rule of clear and distinct perception.
The trademark argument for God's existence. Descartes examines the idea of God in his mind — infinite, all-powerful, all-knowing, supremely perfect — and argues that only an actually existing God could be its adequate cause. A perfect God would not deceive; therefore clear and distinct perception is reliable.
The source of error: not a defect in the intellect, but the will extending beyond what the intellect clearly perceives. Descartes argues that error is always a misuse of freedom — and that the remedy is the discipline of withheld assent.
Two arguments in one meditation: mathematical objects have true natures independent of whether they exist in the world; and God, as supremely perfect, must exist, since existence is a perfection and perfection cannot be lacking in a perfect being.
Bodies exist; mind and body are distinct; the union is real.
Bodies exist; mind and body are really distinct substances; and yet they are also intimately united — felt together in every sensation of pain, hunger, and pleasure. The Sixth Meditation establishes both the distinction and the union, and leaves the tension between them for every subsequent philosopher to inherit.