(Christian) was born at Leipzig 1655, and was well educated, first under his father, and afterwards in the Leipic university. At first he acquiesced in the established doctrines of the schools; but upon reading Puffendorf's "Apology for rejecting the Scholastic Principles of Morals and Laws," light suddenly burst upon his mind, and he determined to renounce all implicit deference to ancient dogmas. He read lectures upon the subject of Natural Law, first from the text of Grotius, and afterwards from that of Puffendorf, freely exercising his own judgment, and, where he saw reason, advancing new opinions. Whilst his father was living, paternal prudence and moderation restrained the natural vehemence and acrimony of the young man's temper, which was too apt to break out, even in his public lectures. But when he was left to himself, the boldness with which he advanced unpopular tenets, and the severity with which he dealt out his satirical censures, soon brought upon him the violent resentment of theologians and professors.

An "Introduction to Puffendorf," which Thomas published in the year 1687, wherein he deduced the obligation of morality from natural principles, occasioned great offence. The following year he became still more unpopular, by opening a monthly literary journal, which he intitled "Free Thoughts, or Monthly Dialogues on various Books, chiefly new;" in which he attacked many of his contemporaries with great severity. The satirical nature of this work was too provoking to be endured; complaints were lodged before the ecclesiastical court of Dresden; the bookseller was called upon to give up the author; and it was only through the intercession of the Marechal that Thomas escaped punishment. The title of the work was now changed; but its spirit remained. A humorous and satirical life of Aristotle, and several other satirical papers, kept alive the flame of resentment, till at length it again burnt forth, on a charge brought against him before the same court by the clergy of Leipzig, for contempt of religion; but he defended himself with such ability, that none of his adversaries chose to reply, and the matter was dropped.

A satirical review, which he wrote, of a treatise "On the Divine Right of Kings," published by a Danish divine; "A Defence of the Sect of the Philists," and other eccentric and satirical publications, at last inflamed the resentment of the clergy against Thomas to such a degree, that he was threatened with imprisonment. To escape the storm which thickened about him, he obtained permission from the Elector of Brandenburg, in whose court he had several friends, that he might read private lectures in the city of Hall. This indulgence being obtained, Thomas became a voluntary exile from Leipzig. After a short interval, he was appointed public professor of jurisprudence, first in Berlin, and afterwards at Hall. In these situations, he found himself at full liberty to indulge his satirical humour, and to engage in the controversies of the times; and as long as he lived, he continued to make use of this liberty in a manner which subjected him to much odium. At the same time, he persevered in his endeavours to correct and subdue the prejudices of mankind, and to improve the state of philosophy. He died at Hall in the year 1728.

Besides the satirical journal already mentioned, Thomas wrote several treatises on logic, morals, and jurisprudence; in which he advanced many dogmas contra- leaves the ground of experiment and rational investigation, and appears among the mystics. His later pieces are in many particulars inconsistent with the former.

His principal philosophical works are, "An Introduction to Aulic Philosophy, or Outlines of the Art of Thinking and Reasoning;" "Introduction to Rational Philosophy;" "A Logical Praxis;" "Introduction to Moral Philosophy;" "A Cure for Irregular Passions, and the Doctrine of Self-Knowledge;" "The new Art of discovering the secret Thoughts of Men;" "Divine Jurisprudence;" "Foundations of the Law of Nature and Nations;" "Dissertation on the Crime of Magic;" "Essay on the Nature and Essence of Spirit, or Principles of Natural and Moral Science;" "History of Wisdom and Folly."

From the specimen given by Dr Enfield of his more peculiar texts (for we have read none of his books), Thomas appears to have been a man of wonderful inconsistency in his opinions; teaching on one subject rational piety and true science, and on another absurdity and atheism. "No other rule (he says) is necessary in reasoning, than that of following the natural order of investigation; beginning with those things which are best known, and proceeding, by easy steps, to those which are more difficult." This is perfectly consistent with the foundation of the Baconian logic; and is indeed the only foundation upon which a system of science can possibly be built. Yet could the man, who professes to proceed from a principle so well established, gravely advance, as conclusions of science, the following absurdities: "Perception is a passive affection, produced by some external object, either in the intellectual sense, or in the inclination of the will. God is not perceived by the intellectual sense, but by the inclination of the will: for creatures affect the brain; but God, the heart. All creatures are in God; nothing is exterior to him. Creation is extension produced from nothing by the divine power. Creatures are of two kinds, passive and active; the former is matter, the latter spirit. Matter is dark and cold, and capable of being acted upon by spirit, which is light, warm, and active. Spirit may subsist without matter, but desires a union with it. All bodies consist of matter and spirit, and have therefore some kind of life. Spirit attracts spirit, and thus feebly operates upon matter united to spirit. This attraction in man is called love; in other bodies, sympathy. A finite spirit may be considered as a limited sphere, in which rays, luminous, warm, and active, flow from a centre. Spirit is the region of the body to which it is united. The region of finite spirits is God. The human soul is a ray from the divine nature; whence it desires union with God, who is love.

Since the essence of spirit consists in action, and of body in passion, spirit may exist without thought: of this kind are light, ether, and other active principles in nature." Fortunately, this jargon is as unintelligible as the categories of Kant, and the blasphemies of Spinoza; for an account of which, the reader is referred to Critical Philosopher in this Suppl., and to Spinoza in the Encycl.