Izak van Gelder enrolled in the Nederlands Israëlitisch Seminarium [Dutch-Jewish Seminary] in Amsterdam at age 13. He lacked the financial resources to complete his studies. The Jewish community in The Hague offered him a teaching position. He continued studying on his own and passed the rabbinical examination in 1906. By then he had five children.
In 1927 Izak van Gelder was appointed rabbi in T…