(Meditations on First Philosophy), written in Latin and thus addressed to the learned. It was followed in 1644 by Principia Philosophiae (Principles of Philosophy), a kind of synthesis of the Discourse on the Method and Meditations on First Philosophy. In 1643, Cartesian philosophy was condemned at the University of Utrecht, and Descartes was obliged to flee to the Hague, settling in Egmond-Binnen. Between 1643 and 1649 Descartes lived with his girlfriend at Egmond-Binnen in an inn. Descartes became friendly with Anthony Studler van Zurck, lord of Bergen and participated in the design of his mansion and estate. He also met Dirck Rembrantsz van Nierop, a mathematician and surveyor. He was so impressed by Van Nierop's knowledge that he even brought him to the attention of Constantijn Huygens and Frans van Schooten. Christia Mercer suggested that Descartes may have been influenced by Spanish author and Roman Catholic nun Teresa of Ávila, who, fifty years earlier, published The Interior Castle, concerning the role of philosophical reflection in intellectual growth. Descartes began (through Alfonso Polloti, an Italian general in Dutch service) a six-year correspondence with Princess Elisabeth of Bohemia, devoted mainly to moral and psychological subjects. Connected with this correspondence, in 1649 he published Les Passions de l'âme (The Passions of the Soul), which he dedicated to the Princess. A French translation of Principia Philosophiae, prepared by Abbot Claude Picot, was published in 1647. This edition was also dedicated to Princess Elisabeth. In the preface to the French edition, Descartes praised true philosophy as a means to attain wisdom. He identifies four ordinary sources to reach wisdom and finally says that there is a fifth, better and more secure, consisting in the search for first causes. Sweden By 1649, Descartes had become one of Europe's most famous philosophers and scientists. That year, Queen Christina of Sweden invited him to her court to organize a new scientific academy and tutor her in his ideas about love. Descartes accepted, and moved to Sweden in the middle of winter. She was interested in and stimulated Descartes to publish The Passions of the Soul. He was a guest at the house of Pierre Chanut, living on Västerlånggatan, less than 500 meters from Tre Kronor in Stockholm. There, Chanut and Descartes made observations with a Torricellian mercury barometer. Challenging Blaise Pascal, Descartes took the first set of barometric readings in Stockholm to see if atmospheric pressure could be