OSTROGSKI, KONSTANTIN VASILIJ. - Prince of Ostrog, born in 1526, died in 1608. Master of vast possessions in Podolia, Galicia, and Volhynia, and voivode (governor) of Kiev, O. was one of the most powerful magnates of the Polish-Lithuanian state. Like his father Costantino before him, he was a patron of the dissident Church and sought to raise its cultural and religious level in collaboration with Prince Andrea Kurbskij and the other refugees from Russia.
To this end he founded at Ostrog a school for the teaching of the classical languages and liberal arts. In the attached printing house, the first complete edition of the Bible in Church Slavonic appeared in 1581. At that time some dissidents conceived the idea of union with the Catholic Church in order better to confront the common danger of Protestantism, and O. initially did not show himself opposed. When the dissident bishops entered into concrete negotiations with Rome, however, O. opposed them, perhaps also somewhat out of resentment at not having been consulted beforehand. He therefore did not accept the union concluded at Brest (1596), and until his death he supported the dissident bishops, which greatly harmed the consolidation of the union. His two sons, Janusz and Andrea, however, entered the Catholic Church while their father was still alive.