DESCARTES TO BERKELEY Princess Elizabeth of Bohemia, one of Descartes’ first readers and shrewdest critics propagator of atheism, and the University of Leiden accused him of the Pelagian heresy Descartes wrote two tracts, which survive, to defend his orthodoxy; but it was really the intervention of inXuential friends that prevented him from being arrested and having his books burnt One of his most supportive friends was Princess Elizabeth, the daughter of the Elector Frederick against whom he had once soldiered He corresponded with her from 1643 until his death, answering (and sometimes failing to answer) her acute criticisms of his writings He gave her much medical and moral advice, and consoled her on the execution of her uncle King Charles I It was to her that he dedicated The Principles of Philosophy The Wrst part of that book summarizes the metaphysics of the Meditations and its three remaining parts deal with physical science, propounding laws of motion and explaining the nature of weight, heat, and light The account given of the solar system is disguisedly heliocentric and discreetly 38