Book I. Introduction: sources and transmission -- The nature of scepticism -- Precursors -- Pyrrho and the socratic tradition -- The scepticism of the Middle Academy -- Carneades and the later sceptical academy -- Secession: the 'fourth academy' and Aenesidemus -- The scepticism of the early empire -- Book II. The ten modes of scepticism -- The modes of Agrippa -- The criterion, signs, and proof -- Causes and explanation -- Scepticism in the medical schools -- Sceptical physics and metaphysics -- The liberal arts -- Sceptical ethics -- The sceptical attitude -- The sceptic way of life -- Biographical appendix -- Glossary.