Preface gives a synopsis of Spinoza, his life, and where he was at during this time period. The book gives a huge depth into Cartesian Philosophy which is the philosophical doctrine of Rene Descartes. It also speaks of metaphysics in relation to Spinoza and Cartesian Philosophy. Baruch or Benedict de Spinoza was a Dutch philosopher of Portuguese Jewish origin. Revealing considerable scientific aptitude, the breadth and importance of Spinoza's work was not fully realized until years after his death. Today, he is considered one of the great rationalists of 17th-century philosophy, laying the groundwork for the 18th century Enlightenment and modern biblical criticism. By virtue of his magnum opus, the posthumous Ethics, in which he opposed Descartes' mind¿body dualism, Spinoza is considered to be one of Western philosophy's most important philosophers. Philosopher and historian Georg Wilhelm Friedrich Hegel said of all modern philosophers, "You are either a Spinozist or not a philosopher at all." All of Spinoza's works were listed on the Index Librorum Prohibitorum (List of Prohibited Books) by the Roman Catholic Church. Spinoza lived quietly as a lens grinder, turning down rewards and honors throughout his life, including prestigious teaching positions, and gave his family inheritance to his sister. Spinoza's moral character and philosophical accomplishments prompted 20th century philosopher Gilles Deleuze to name him "the 'prince' of philosophers." Spinoza died at the age of 44 of a lung illness, perhaps tuberculosis or silicosis exacerbated by fine glass dust inhaled while tending to his trade. Spinoza is buried in the churchyard of the Nieuwe Kerk on Spui in The Hague.