To regulate thought required an intellect of a different order from that of Balzac, "emperor of orators." It was the task of RENE DESCARTES (1596-1650). A child of delicate health, born at La Haye, near Tours, he became, under Jesuit teachers, a precocious student both in languages and science. But truth, not erudition, was the demand and the necessity of his mind. Solitary investigations in mathematics were for a time succeeded by the life of a soldier in the Netherlands and Holland. The stream of thought was flowing, however, underground. Suddenly it emerged to light. In 1619, when the young volunteer was in winter quarters at Neuburg, on the Danube, on a memorable day the first principles of a new philosophical method presented themselves to his intellect, and, as it were, claimed him for their interpreter. After wanderings through various parts of Europe, and a period of studious leisure in Paris, he chose Holland for his place of abode (1629), and though often shifting his residence, little disturbed save by the controversies of philosophy and the orthodox zeal of Dutch theologians, he gave his best hours during twenty years to thought. An invitation from Queen Christina to the Swedish court was accepted in 1649. The change in his habits and the severity of a northern winter proved fatal to the health which Descartes had carefully cherished; in February of 1650 he was dead. The mathematical cycle in the development of Descartes' system of thought preceded the metaphysical. His great achievements in analytical geometry, in optics, in physical research, his explanation of the laws of nature, and their application in his theory of the material universe, belong to the history of science. Algebra and geometry led him towards his method in metaphysical speculation. How do all primary truths verify themselves to the human mind? By the fact that an object is clearly and distinctly conceived. The objects of knowledge fall into certain groups or series; in each series there is some simple and dominant element which may be immediately apprehended, and in relation to which the subordinate elements become intelligible. Let us accept nothing on hearsay or authority; let us start with doubt in order to arrive at certitude; let us test the criterion of certitude to the uttermost. There is one fact which I cannot doubt, even in doubting all--I think, and if I think, I exist--"Je pense, donc je suis." No other evidence of this is needed than that our conception is clear and distinct; in this clearness and distinctness we find the principle of certitude. Mind, then, exists, and is known to us as a thinking substance. But the idea of an infinite, perfect Being is also present to our intellect; we, finite, imperfect beings, could not have made it; unmake it we cannot; and in the conception of perfection that of existence is involved. Therefore God exists, and therefore the laws of our consciousness, which are His laws, cannot deceive us. We have