from Gustav Mahler: Memories and Letters, by Alma Mahler, Third ed., page 44

He had been baptized before he left Hamburg (on 23rd February 1897, at the Kleine Michaelskirche). He was afraid lest otherwise he might find it difficult as a Jew to get his engagement in Vienna. His account of his recalcitrance and doubts during his instruction in the Catholic faith, and of the embarrassing questions he put to his catechist and the sudden surging up of Old Testament pride was delightful. Then he arrived in Vienna, where the fullest powers were guaranteed and where he hoped to carry out at last all his far-reaching plans for stage and orchestra.