This book systematically traces the development of the idea that the improvement of human understanding requires public activity.

Preface; List of abbreviations; 1. Introduction: the enlightened mind; 2. Descartes: willful thinking; 3. Hobbes: passionate thinking; 4. Locke: uneasy thinking; 5. Enthusiasm: inspired thinking; 6. Spinoza: resolute thinking; 7. Leibniz: trained thinking; 8. Conclusion: the public mind; Bibliography; Index.