Karl Leonhard Reinhold (26 October 1757 – 10 April 1823) was an Austrian philosopher who helped to popularise the work of Immanuel Kant in the late 18th century. His "elementary philosophy" (Elementarphilosophie) also influenced German idealism, notably Johann Gottlieb Fichte, as a critical system grounded in a fundamental first principle. He was the father of Ernst Christian Gottlieb Reinhold (1793–1855), also a philosopher. Life Reinhold was born in Vienna. In late 1772, at the age of fourteen he entered the Jesuit college (Roman Catholic seminary) of St. Anne's Church, Vienna (Jesuitenkollegium St. Anna). He studied there for a year, until the order was suppressed in 1773, at which time he joined a similar Viennese Catholic college of the order of St. Barnabas, the Barnabitenkollegium St. Michael. In 1778 he became a teacher at the Barnabitenkollegium, on August 27, 1780, he was ordained as a priest, and on April 30, 1783, he became a member of the Viennese Freemasonry lodge "Zur wahren Eintracht." Finding himself out of sympathy with monastic life, he fled on November 19, 1783 to Leipzig, where he converted to Protestantism. In 1784, after studying philosophy for a semester at Leipzig, he settled in Weimar, where he became Christoph Martin Wieland's collaborator on the German Mercury (Der Teutsche Merkur), and eventually his son-in-law. Reinhold married Wieland's daughter Sophia Catharina Susanna Wieland (October 19, 1768 – September 1, 1837) on May 18, 1785. In the German Mercury Reinhold published, in the years 1786–87, his Briefe über die Kantische Philosophie (Letters on the Kantian Philosophy), which were most important in making Immanuel Kant known to a wider circle of readers. As a result of these Letters, Reinhold received a call to the University of Jena, where he taught from 1787 to 1794. In 1788, Reinhold published Hebräischen Mysterien oder die älteste religiöse Freymaurerey (The Hebrew Mysteries; or, The Oldest Form of Freemasonry) under the pseudonym Decius. The fundamental idea of this work is that Moses derived his system from the Egyptian priesthood. He presented them in the form of two lectures in Leipzig that year. In 1789 he published his chief work, the Versuch einer neuen Theorie des menschlichen Vorstellungsvermögens (Essay towards a New Theory of the Faculty of Representation), in which he attempted to simplify the Kantian theory and make it more of a unity by basing it on one principle, Reinhold's principle of consciousness (Satz des Bewußtseins). In