An atheistical writer, son of a Portuguese Jew, born at Amsterdam, 1638. He studied medicine and theology; but his religion was so loose, and his inquiries for the reason of every thing which he was to believe, became so offensive to the rabbies, that he was thrust out of the synagogue. In consequence of this, he became a Christian, and was baptized; but his conversion was insincere, and though, during his life, he did not openly profess himself an atheist, his posthumous works plainly proved him such. He died, of a consumption, at the Hague, February, 1677, aged forty-five. He is the founder of a regular system of atheism, and by his hypothesis he wished to establish that there is but one substance in nature, which is endowed with infinite attributes, with extension and thought; that all spirits are modifications of that substance; and that God, the necessary and most perfect being, is the cause of all things that exist, but does not differ from them. These monstrous doctrines, though not new, were thus built into a regular system by this extraordinary man, who is said in other respects to have been of a good moral character in private life, benevolent, friendly, and charitable. His conduct was marked by no licentiousness or irregularity; but he retired from the tumults of Amsterdam to a more peaceful residence at the Hague, where curiosity led princes, philosophers, and learned men, to see and to converse with this bold assertor of atheism.