From the Introduction: "Every biography is a story of adventure. The energetic
personalities of the world represent an adventure in living. The philosophical personalities, on
the other hand, represent an adventure in thinking. And when we examine the lives of the
philosophers we find that the procession of a man's thoughts can be as exciting a spectacle
as the pageantry of a man's deeds."

Included are these great thinkers: Plato and Socrates, Aristotle, Epicurus, Marcus Aurelius,
Thomas Aquinas, Francis Bacon, Descartes, Spinoza, Locke, Hume, Voltaire, Kant, Hegel,
Schopenhauer, Emerson, Spencer, Nietzsche, William James, Henri-Louis Bergson, and
Santayana.