Diest, Heinrich a German theologian, was born at Altena, in Westphalia, in 1595. He studied at Dortmund, Siegen, and Basle, and continued his studies at; Heidelberg; but was obliged to leave that city at the time of the religious disputes, and returned to Basle, to pass his examinations for the doctor's degree, in 1621. Until 1624 he lived at Leyden as a private teacher. He was appointed minister of the Gospel at Emmerich, and in 1629 professor of theology and Hebrew in the University of Harderwick. In 1641 he went to Deventer in the same capacity, and died there in 1673, leaving, among many other works, De Ratione Studii Theologici (Harderwick, 1634): — Oratio Inauguralis (Deventer, 1640): — Funda Davidis (1646): — Pedum Davidis (1657). See Hoefer, Nouv. Biog. Generale, s.v.