Mordecai Kaplan was an influential American rabbi and educator, born in 1881 in Lithuania. He is best known for founding the Reconstructionist Judaism movement, which emphasizes a progressive approach to Jewish life and thought. Kaplan believed that Judaism should evolve with the times while maintaining its core values and traditions. Kaplan's ideas were rooted in the belief that Jewish identity is shaped by culture, history, and community. He authored several important works, including his book, Judaism as a Civilization, which outlines his vision of Judaism as a living, dynamic civilization rather than just a religion. Kaplan passed away in 1983, leaving a lasting impact on Jewish thought.