1. Introduction; 2. The predicate calculus and the system; 3. Peano arithmetic and its subsystems; 4. Two-sorted logic and complexity classes; 5. The theory V0 and AC0; 6. The theory V1 and polynomial time; 7. Propositional translations; 8. Theories for polynomial time and beyond; 9. Theories for small classes; 10. Proof systems and the reflection principle; 11. Computation models.