Heidanus, Abraham professor of theology at Leyden, was born at Frankenthal, in the Palatinate, Aug. 10,1597. He was educated at Amsterdam and Leyden, and in 1627 was appointed to a pastoral charge in the latter city. In 1647 he became professor in the University of Leyden. Heidanus held a mild view of the doctrine of predestination, and adopted the Cartesian philosophy, of which he became a strong advocate. This involved him in various controversies, in which he bore himself admirably. Yet, when nearly eighty years old, he was dismissed from his professorship by the curators of the University. He died at Leyden Oct. 15, 1678. His Corpus Theologiae Christianae was posthumously published (1686, 2 vols. 4to).