 After graduation Brentano prepared to take his vows; he was ordained a Catholic priest in 1864. Nevertheless he continued his academic career at the University of Würzburg, where he presented his Habilitationsschrift on The Psychology of Aristotle in 1867. Despite reservations in the faculty about his priesthood he eventually became full professor in 1873. During this period, however, Brentano struggled more and more with the official doctrine of the Catholic Church, especially with the dogma of papal infallibility, promulgated at the first Vatican Council in 1870. Shortly after his promotion at the University of Würzburg, Brentano withdrew from the priesthood and from his position as professor.