The seventeenth century has been called the heroic age of rationalism in Western Europe, and the term does indeed accurately express the three essential features of the thought of the period. These were, first, the alliance between the traditions of Galileo and of Descartes— between the new mathematico-mechanical science and the idea of natural law—second, the divorce of political thought from theology, and finally, the capacity of its great minds for creative thought. For there are few centuries so rich in creative philosophic ability, or in which political theory so boldly aspires to the utmost heights of intellectual speculation. But the spell cast by the great philosophers of the period presents a danger to the historian of its thought. He tends much too easily to confuse their originality with their influence, their future importance with their authority among their contemporaries. Many of their most important ideas are far ahead of their time—ideas which could not be fully developed in the intellectual climate of the age and did not leave their full mark on the history of thought until much later. The importance of Spinoza was first fully revealed by Goethe, that of Leibniz by the German idealists. That is why, more than in any other period since then, the history of ideas cannot be considered in vacuo, but must be related to the changing conditions of an age in which the basic problems of political life constantly take on new forms.