The idea of perpetual peace was first suggested in the 18th century, when Charles-Irénée Castel de Saint-Pierre published his essay "Project for Perpetual Peace" anonymously while working as the negotiator for the Treaty of Utrecht. However, the idea did not become well known until the late 18th century. The term perpetual peace became acknowledged when German philosopher Immanuel Kant published his 1795 essay Perpetual Peace: A Philosophical Sketch.