Lydius, Balthasar a Dutch theologian of German origin, was born at Umstadt, near Darmstadt, about 1577; studied at Leyden; became pastor at Streefkerk in 1602, and in 1608 at Dordrecht. He was present at the Synod of Dort. He died in 1629. Lydius was a violent opponent of the Remonstrants. Of his literary labors, one deserves special mention, Waldensisa (now very rare, Rotterdam, 1616-17; 2d ed. Amsterdam, 1623, 2 volumes, 8vo), in which he seeks to show an intimate connection between the Moravians and Waldensians. See Herzog, Real-Encyklop. 20:63, 64.