This is a gripping biography of the iconic French philosopher, Rene Descartes which places his life and work firmly into the context of his own times as well as showing how his work remains relevant for modern times. Descartes was both fortunate and unfortunate to live in violently exciting times, the clash within the Christian faith between the Catholic Church and the various Protestant churches savagely intensified the strategic and political underpinning of the Thirty Years War. Descartes may have had more involvement in the early events of this war, A.C.Grayling makes a persuasive case that Descartes did undercover work for the Jesuits. This created the situation where Descartes would have been opposed to French interests in the war which may well explain his hurried departure from France and his long sojourn in the Netherlands. One of the very striking aspect of the era was that scientific thinking based on observation and experiment was emerging and challenging the orthodox religious view of the world. This was a potentially fatal route to take, Descartes is one of the people who found a way to safely separate the two so science could be freed from the charge of heresy and the possibility of being burned at the stake. A.C.Grayling conveys the tremendous pressure that Descartes was under to be true to his passionately held religious beliefs and the equally passionate desire he had to pursue understanding and knowledge. The book explains the originality and urgency of Descartes though in a way that is comprehensible and exciting to a lay reader without ever reducing them to parody. The character of Descartes comes to life very strongly and this gives the ideas clarity and force. Descartes was a prickly and proud man, he was constantly trying to ensue that his ideas got into circulation without distortion and at the same time not cause offence. A.C.Grayling conveys the excitement of the whole process and brings out the wonderfully human man behind the phrase” I think, therefore I am” and shows why the ideas surrounding that phrase are still thrilling and exciting today.