Complex sentence: When his father became a village rabbi again in 1921, Singer went back to Warsaw, where he entered the Tachkemoni Rabbinical Seminary and soon decided that neither the school nor the profession suited him.
Split into simpler sentences: When his father became a village rabbi again in 1921, Singer returned to Warsaw. He entered the Tachkemoni Rabbinical Seminary and soon decided that neither the school nor the profession suited him.