Vernünfftige Gedancken von
dem Gebrauche der Theile in
Menschen, Thieren und Pflantzen,
den Liebhabern der Wahrheit
Frankfurt and Leipzig: Renger, 1730
The eighteenth-century substitution of a new faith in reason, "science," and the future for that of revealed religion was facilitated by the establishment of new systems of logical analysis. When philosophers such as Christian Wolff (1679-1754) changed systems of formal logic into metaphysics, they challenged the very basis of religious authority and invoked vigorous responses. In 1706, Wolff, a follower of Leibniz, was appointed professor of mathematics and natural philosophy at the University of Halle, then a center of Pietism. Wolff soon antagonized many colleagues by insisting that religious truths be grounded in mathematical certitude. Following years of harassment by his opponents, Wolff was ordered out of Prussia by Frederick William I and, in 1731, left for Saxony and a later post at Marburg. Among Wolff's most important writings was Vernünfftige Gedancken von dem Gebrauche der Theile (1724), a work on physiology which reflects his comprehensive view of philosophy as embracing all fields of knowledge.
Christian August Crusius
Weg zur Gewissheit
der menschlichen Erkenntnis
Leipzig: Johann Friedrich Gleditsch, 1747
Integral to the philosophies of Leibniz and Wolff was a deterministic concept of the individual and the world which challenged traditional theological viewpoints. Among those responding to these philosophies was the theologian Christian August Crusius (1715-1775. In Weg zur Gewissheit und Zuverlässigkeit, one of Crusius' major works, he attacked Leibniz and Wolff on the basis of the moral evils which he feared would result from their systems of determinism. Crusius was above all concerned with the implications of those systems relating to the freedom of the will. His criticisms of Wolff in particular had much influence upon the young Kant who, in his Kritik der praktischen Vernunft, refers to Crusius' ethical doctrines with respect.
Friedrich Heinrich Jacobi
Ueber die Lehre des
Spinoza in Briefen an den
Herrn Moses Mendelssohn
Breslau: Gottlieb Löwe, 1785
In this first edition of the work which brought him into prominence as a philosopher, Friedrich Heinrich Jacobi (1743 1819) criticized the system of Baruch Spinoza (1622-1677) for its suspected atheism. Jacobi also believed that the philosophies of Spinoza, Leibniz, and Wolff; being deterministic systems of metaphysics, fell prey to fatalism. Because he insisted on the importance of faith as a unifying force in philosophy, Jacobi was attacked by Moses Mendelssohn (1729-1786) and other thinkers in Berlin for his attempts to reintroduce the antiquated concept of unreasoning belief. Among the charges levelled at Jacobi were that he was an enemy of reason, a Pietist, and worst of all a Jesuit in disguise.
Gotthold Ephraim Lessing
Nathan der Weise
Berlin: Christian Friederich Voss and Son, 1779
Among the most influential works of the celebrated dramatist, critic, and philosopher Gotthold Ephraim Lessing (1729 1781) was Nathan der Weise (1779), a finely crafted play whose theme of religious tolerance was grounded firmly in contemporary rationalism. Lessing embodied his arguments for toleration in the famous parable of the three rings narrated by Nathan, the wise Jew. The story of the three sons representing Judaism, Christianity, and Islam who are potential holders of a magical ring, suggests that the absolute truth of any religious faith cannot be proven on historical grounds, and that the search for truth takes precedence over the possession of truth. Nathan der Weise thus argues for a nondogmatic view of religion, based on a shared humanity above the accidents of race and creed.
Schreiben an den
Herrn Diaconus Lavater zu Zürich
Berlin and Leipzig, 1770
The inspiration for the character Nathan the Wise may have been provided by Lessing's good friend, the renowned Jewish philosopher Moses Mendelssohn. One of the foremost figures of the eighteenth century, Mendelssohn drew acclaim as the "German Plato" for his discussion of the immortality of the soul in Phädon (1767). The Phädon led to a dispute with the Swiss theologian Johann Kaspar Lavater (1741 1801) concerning certain proofs of Christian dogma proposed by the Swiss philosopher Charles Bonnet (1720 1793). In his quest to convert Mendelssohn, Lavater challenged the Jewish philosopher to refute Bonnet's proofs and to defend his own tradition and faith. In response, Mendelssohn composed his Schreiben an den Herrn Diaconus Lavater, in which he eloquently related his philosophical views to his religious beliefs. Lavater's challenge served to strengthen Mendelssohn's commitment to Judaism, and he dedicated the remainder of his life to the emancipation of the Jews.
Johann Wolfgang von Goethe
Strassburg: Johann Heinrich Heitz, 
In his early days as a student at the University of Leipzig, the great poet, dramatist, and philosopher Johann Wolfgang von Goethe (1749 1832) spent most of his time composing poetry and studying literature. In 1768 Goethe was stricken by a severe illness, forcing the termination of his studies at Leipzig and the return to his home in Frankfurt. After a long period of convalescence, Goethe was sent by his father to earn a degree in law at the University of Strassburg. Goethe would have preferred to resume his literary studies but agreed to his father's request, studying at Strassburg from 1770 1771. On August 6 of 1771, Goethe was awarded his degree following the successful defense of Positiones juris, a twelve-page dissertation containing fifty-six maxims on the nature and function of law. Goethe soon returned home to begin a career as an advocate but instead became a leader in the literary revolt then brewing against the principles of the Enlightenment.
Johann Gottfried von Herder
Berlin: Christian Friedrich Voss and Son, 1789
Goethe had put into practice many of the ideas of the philosopher and literary critic Johann Gottfried von Herder (1744 1803). Herder was a pioneer of the Sturm und Drang and a critic who changed the literary tastes of a generation. Contained in Zwei Preisschriften is "Abhandlung über den Ursprung der Sprache" (1772), Herder's important essay on the origin of language which helped establish the foundations for the comparative study of philology, religion, and mythology. Herder argued that primitive language was an imitation in sound and imagery of natural phenomena, resulting in the personification of nature and constituting a living mythology. In contrast to the Enlightenment, he ascribed a positive role to religion in human history and praised the simplicity and spontaneity of primitive times against the complexity and rigidity of the modern world.