[1] After studying philosophy and theology at the Catholic University of Leuven, he entered the Benedictine Abbey of Affligem in 1609, took solemn vows on 14 May 1611, and was ordained priest in 1613.
[1] Jacob Boonen, who had succeeded Hovius as archbishop and abbot in 1620, desired to join the monastery to the new Congregation of St. Vannes, in Lorraine, which had a stricter constitution than Bursfeld.
[2] After some hesitation, van Haeften agreed to the change, and on 18 October 1627, began his novitiate under the direction of a monk of the Congregation of Lorraine.
The new reform enjoined perpetual abstinence, daily rising at two o'clock in the morning, and manual labour joined with study.
Professor Carme López Calderón suggests that the engravings in Van Haeften's Schola cordis were used as a reference in the decoration of the "Chapel of Nuestra Señora de los Ojos Grandes" in Lugo Cathedral.