It is the first book that examines historically, politically and anthropologically the multiple movements and diverse trends of the French Left from the Enlightenment era to the present day. The Left is associated with the idea of progress in the late 18th century, with human rights during the Revolution, with parliamentarism during the period of the Thermidorian Monarchy, with universal suffrage in 1848, with the separation of Church and State during the Third Republic, with the dehumanization of labor during the Popular Front, with the power play during the presidency of Mitterrand. Zuliar distinguishes four Lefts: the liberal, the Jacobin, the collectivist, the libertarian. Each period is illuminated by parallel portraits (in the manner of Plutarch) of Voltaire and Rousseau, Robespierre and Danton, Lamartine and Hugo, Clemenceau and Jaurès, up to Sartre and Camus or Mandès-France and Mitterrand.