'Core books' are those which are the keystone of Gurdjieff's teaching, including all editions of Gurdjieff's own writings and P.D. Ouspensky's detailed summary of Gurdjieff's teaching up to 1921, In Search of the Miraculous. We also include The Reality of Being by Jeanne de Salzmann (1889–1990), a succinct and deeply personal testament to her own transmission of the teaching throughout her life.