Professor Susskind continues the discussion of phase transitions beginning with a review of the Ising model and the mean field approximation, and then presents the temperature and magnetic field parameters of the phase transition of a magnetic material. He then moves to the physics of the liquid-gas phase transition and develops the mathematical analogy between this case that that for a magnetic material. Professor Susskind finishes the Theoretical Minimum series of courses by taking questions from the class, which leads to a discussion of the anthropic principle and fine tuning.