Ludwig Crocius was born in
Laasphe, the son of Paul Crocius (1551–1607). He was at one time tutor to the sons of the counts of
Nassau-Dillenburg and
Wittgenstein-Berleburg. From 1583, he was minister and Superintendent in Laasphe. Crocius was the author of a book of Protestant martyrology
Groß Matyrbuch und Kirchenhistorien (1606).
Johann Crocius was his younger brother. His grandfather Matthias Crocius (1479–1557) had been a minister in
Zwickau, and was close to
Martin Luther and
Philipp Melanchthon. Crocius studied at
Herborn Academy, and then from 1603 studied theology at the
University of Marburg where he graduated M.A. in 1604. On 5 September 1607 his father died, vacating his position as preacher and inspector of the county of
Katzenelnbogen in
Langenschwalbach—Crocius succeeded him, but in 1608 he asked for leave from
Moritz of Hesse-Kassel for further study. Crocius went to the universities in Bremen, Marburg and Basel. On 4 April 1609, he graduated D.D. in Basel, and travelled on to Geneva, in order to study there further. From Geneva, he returned to Bremen and the St. Martini church as first preacher and teacher of philosophy and theology professor at the Gymnasium Illustre, from 1610. He turned down later offers of positions made by
John Sigismund, Elector of Brandenburg (1615) and the Landgrave Moritz of Hesse-Kassel (1618), and also a chance to become General superintendent for
Silesia. From 1630 to 1639, and from 1647 to his death, he was a prorector at the High School Illustre. He corresponded with
Samuel Hartlib and
John Dury, and with
Gerardus Vossius. In 1651 Crocius suffered an attack of
apoplexy, but he remained until 14 May 1652 at his post of preacher in the Liebfrauenkirche church. He taught at the Gymnasium Illustre up to his death, which occurred in Bremen. ==Synod of Dort==