1502-1568. Mennonite theologian. Son of a Dutch priest, he was well educated and able to use Latin, Greek, and some Hebrew, though it is not known where he studied. He left the Franciscans and converted to Anabaptism in 1533. At the wish of the brethren at Groningen, his elder brother Obbe ordained him an elder in 1534. With Obbe and Menno,* he was a firm opponent of Münsterite doctrines. He wrote extensively and systematically and was probably the leading theologian of the early Dutch and N German Mennonites. But largely because of his greater severity and rigidity, he was somewhat less influential than , and was partially responsible for schism within the Mennonite brotherhood.