1. Introduction, 2. The Mathematical Path, 3. The Aesthetic Path, 4. New Aesthetic Sensibilities in Italian and French Architecture, 5. The Ancient Concept of Symmetry in Scientific Contexts in Early Modern Times and Its Association with Harmony, 6. The Treatment of Symmetry in Natural History (1738-1815), 7. Leonhard Euler (1707-1783) and Immanuel Kant (1724-1804): 'revolutions' that did not happen, 8. Legendre's Revolutionary Definition of Symmetry...