[Footnote 1: Rüdiger: _Disputatio de eo quod Omnes Idea Oriantur a Sensione_, 1704; _Philosophia Synthetica_, 1707; _Physica Divina_, 1716; _Philosophia Pragmatica_, 1723.] [Footnote 2: Crusius: _De Usu et Limitibus Principii Rationis_, 1743; _Directions how to Live a Rational Life_ (theory of the will and of ethics), 1744; _A Sketch of the Necessary Truths of Reason_, 1745; _Way to the Certainty and Trustworthiness of Human Knowledge_, 1747.] [Footnote 3: J.J. Brucker _(Historia Critica Philosophiae_, 5 vols., 1742-44; 2d ed., 6 vols., 1766-67) was a pupil of Budde.] %3. The Illumination as Scientific and as Popular Philosophy.% After a demand for the union of Leibnitz and Locke, of rationalism and empiricism, had been raised within the Wolffian school itself, and still more directly in the camp of its opponents, under the increasing influence of the empirical philosophy of England,[1] eclecticism in the spirit of Thomasius took full possession of the stage in the Illumination period. There was the less hesitation in combining principles derived from entirely different postulates without regard to their systematic connection, as the interest in scholastic investigation gave place more and more to the interest in practical and reassuring results. Metaphysics, noëtics, and natural philosophy were laid aside as useless subtleties, and, as in the period succeeding Aristotle, man as an individual and whatever directly relates to his welfare--the constitution of his inner nature, his duties, the immortality of the soul, and the existence of God--became the exclusive subjects of reflection. The fact that, besides ethics and religion, psychology was chosen as a favorite field, is in complete harmony with the general temper of an age for which self-observation and the enjoyment of tender and elevated feelings in long, delightfully friendly letters and sentimental diaries had become a favorite habit. Hand in hand with this narrowing of the content of philosophy went a change in the form of presentation. As thinkers now addressed themselves to all cultivated people, intelligibility and agreeableness were made the prime requisites; the style became light and flowing, the method of treatment facile and often superficial. This is true not only of the popular philosophers proper--who, as Windelband pertinently remarks (vol. i. p. 563), did not seek after the truth, but believed that they already possessed it, and desired only to disseminate it; who did not aim at the promotion of investigation, but the instruction of the public--but to a certain extent, also, of those who were conscious of laboring in the service of science. Among the representatives of the more polite tendency belong, Moses Mendelssohn[2] (1729-86); Thomas Abbt (_On Death for the Fatherland_, 1761; _On Merit_, 1765); J.J. Engel (_The philosopher for the World_, 1775); G.S. Steinbart (_The Christian Doctrine of Happiness_, 1778); Ernst Platner