Prologue: Philosophy as vision -- pt. 1. Ancient visions: 1. First stage in the life of reason: naturalism -- 2. Second stage in the life of reason: humanism -- 3. Third stage in the life of reason: naturalistic humanism -- 4. Fourth stage in the life of reason: rationalistic mysticism -- pt. 2. Theocratic interlude -- pt. 3. Modern visions: 1. Naturalistic rationalism -- 2. Humanistic empiricism -- 3. Humanistic rationalism -- 4. Naturalistic empiricism and the Bergsonian reaction -- Epilogue: From each great vision.