Tersteegen, Gerhard the mystic aid sacred poet, was born at-Meurs, on Nov. 25,1697. He early acquired a thorough knowledge of ancient languages, including the Hebrew, and friends advised his preparation for a. learned career; but, his father having died, his mother was induced, from domestic considerations, to choose a mercantile life for him instead. He was apprenticed to his brother-in law at Mülheim in 1713, and in the following year was powerfully wrought upon by the grace of God. Mülheim was at that time the scene of an exalted and vigorous piety which was kept alive through, the holding of weekly convocations, and made itself felt in all the affairs of life. These convocations became an occasion of offence to the Church at large, and Hoffmann, the Mülheim pastor, was cited before the Classis of Duisburg, which decided that he must refrain from holding them in future, and induced the Synod of Cleves to take similar action. Nothing has been found, however, to show that Hoffmann was guilty of heterodoxy, or that the convocations served any other purpose than that of leading many souls to Christ. In spite of these inquisitorial measures, the convocations. were obstinately continued at Mülheim, and Tersteegen, for his part, was alienated from the Church to such a degree as to refrain from participating in the public worship, and particularly in the sacrament of the Lord's supper, of which evident sinners were allowed to partake. He finished his apprenticeship, but two years afterwards, in 1719, under the impulse of religious sentiment, renounced his business for one of a more retired character. He now became a ribbon-weaver and an ascetic. He had no companion save the girl who wound his silk. His clothing was poor, his food scanty and simple; but his charities, whatever might be his income, were numerous. He considered this ascetical, hermit life the ideal condition of a Christian on the earth, and for a time endured its trials and privations with unwavering confidence in the care of his heavenly Father; but gradually he became the prey of internal anxieties which tortured him during five years with but occasional and transient interventions of hope. But in 1724 that period of suffering came to its close. He celebrated the return of his Savior's smile in the hymn Wie bist Du mir sonnig gut, mein Hohepriester Du and entered into a covenant with his Lord which he signed with his own blood-probably in imitation of the marquis de Renty, whose life he had treated with great pleasure in his book Leben heiliger Seelen, 1, 3.
With the conclusion of this period of spiritual dark-: ness his preparation came to an end. He was thenceforward, though much against his will, thrown among men and obliged to take an active part in the affairs of religion. He resided with his brother, and while employed in the tuition of that brother's children was led to undertake a work which initiated his career as a mystical writer-the Unparteiischer Abriss christlicher Grundwahrheiten, a catechetical manual, first printed in 1801 and again in 1842. In this book he evidently leaned on the French mystic Pierre Poiret (q.v.) as respects both its arrangement and matter. The first three centuries of the Church are represented as having been pure, and the succeeding ages, from n Constantine to the 15th century, as a period of great apostasy. The light broke through with power in the Reformation, but afterwards again declined. Christianity exists more generally in name than in fact. Upon this work followed a number of translations and' prefaces, in the preparation of which Tersteegen was accustomed to spend the time after six o'clock in the evening. The list includes Labadie, Manuel de Piett (with preface dated Mülheim, May 21, 1726); Jean de Bernieres Louvigny's works (Das verborgene Leben mit Christo in Gött, etc., with preface dated Dec. 18, 1726); Thomas a Kempis, Imitatio Christi; Gerlach Petersen, Soliloquia (1727). In 1733 he began the publication of the work entitled Auserlesene Lebensboschr. heil. Seelen, the final (third) volume of which appeared in 1753, followed by a second edition of the whole work in the next year. The saints so commemorated belong altogether to the Roman Catholic communion a fact which Tersteegen excused on the ground that others had rendered a similar service to Protestantism but there is satisfactory proof that he possessed an especial fondness for the peculiar piety cultivated by the mystical ascetics of the former Church. In 1749 he published a translation of a poetical composition by Madame Guyon illustrative of the inner life, and with this work completed the series of his mystical writings. In them all he takes Poiret-sometimes Godfrey Arnold (q.v.) also for his master. His mystical tendency is sometimes exaggerated into Quietism (q.v.) in them, so that he can speak in glowing terms of approval of a state of perfect rest for the soul which begins and continues through the direct operation of God on the soul without any mediation whatever, even though it be that of Scripture or of Christ.
Tersteegen yielded to the persuasions of Hoffmann and others, and began to address public assemblies at about the time when his first literary efforts were put forth. In 1728 he renounced his handicraft and gave himself wholly to the care of souls. His wants were supplied by the contributions of friends and by several legacies, so that he was even able to exercise a liberal benevolence. His advice was desired by great numbers of people living everywhere in the territories of Cleves and Berg. Otterbeck, a farm between Mülheim and Elberfeld, became a station where a number of his' adherents lived together in the practice of industry, self renunciation, and piety. He furnished them twelve rules of conduct (given at the close of vol. 3 of his letters), and watched over them with jealous care. A work written in their behalf in 1727 became a bulwark against Antinomianism (q.v.), and saved them from the excesses into which other, but kindred, associations were drawn. A second center of his influence was Elberfeld, and subsequently Barmen. This region was troubled with the fanatical influence of Eller (q.v.) and his supporters. To counteract that influence, Tersteegen wrote an effectual admonition (comp. Wegder Wahrheit, 11). Solingen was a third station, and it was there that Tersteegen delivered the only sermon ever preached by him. At Crefeld extraordinary manifestations accompanied a work of grace, which were controlled through his judicious counsel. He was also brought into relations with the Moravian Brotherhood, and was solicited by Zinzendorf, Dober, and other leaders to cast in his lot with theirs, but he steadily refused, less on the ground of their unusual methods than because he believed their teachings to be erroneous. He charged them with identifying sanctification with justification and with misrepresenting the legal and the evangelical elements of religion. He found in them no earnest striving in the way of a progressive sanctification, and no willingness to receive the doctrine of the necessity for thorough going self-denial and persistent watchfulness and prayer, which they denounced as legalism. His position hindered the Moravians from securing an establishment in the regions of the Lower Rhine.
In 1740 an occurrence at Solingen led the authorities to issue a positive prohibition of conventicles, and Tersteegen saw his extended and successful labors interrupted. During ten years he was able to hold public gatherings only in Holland, whither he frequently journeyed; but his correspondence and private labors increased enormously. He regarded the prohibition as a trial, and counseled submission. But when in 1750 a new awakening took place, he began once more to assert the right of "private assemblies." He wrote an awakening sermon at this time on 2Co 5:14, which was favorably received and led to the ultimate publication of a series of discourses under the title Geistliche Briosamen, etc. (1773, 2 vols. in 4 pts.). They represent the culmination of his powers, and are equaled in contents and method by but few of the productions of his contemporaries.
The favor with which these sermons were received brought their author into general notice, and led to the appointment of a royal commissioner to inquire into, the work of Tersteegen among his adherents. The person selected for this duty was a member of the high consistory named Hecker, a native of the Rhine provinces and a friend to Tersteegen. Through him the latter was induced to draw up a confession of his faith, and subsequently a critique of the Cuvres du Philosophe de Sans-souci, which elicited the approval of the king. A steady approximation on the part of Tersteegen and his friends towards the State Church is noticeable from this period, but he was never formally identified with it because of its tolerance of open sinners as communicants. He discussed this question in a tract issued in 1768, shortly before his decease. A feeble and, broken constitution troubled him all his days; but he attained to the age of seventy- two years, passing away in a quiet slumber April 3,1769.
As a poet, Tersteegen was prolific, and thoroughly, though evangelically, mystical. His apprehension of the idea of self-renunciation and a blessed loss of self in God was so profound as to prevent the Church of his day from appreciating his merit. His hymns are now found, however, in the collections of every German Church. His principal collection of hymns was published in 1729 under the title Geistliches Blumengdrtleins (15th ed. Essen, 1855). He also rendered the mystical poems of Labadie into German, and contributed to the collection known as Gottgeheiligtes
Harfenspiel d. Kider, etc. His works have been published in Germany by G. D. Badecker.. His life was written by Dr. Kerlem; (Mülheim, 1853), and Gobel in his Geschichte d.christl. Lebens, etc., 3, 289-447. See Herzog, Real-Encyklop. s.v.