Felix Adler (1851-1933) was a prominent American intellectual, educator, and social reformer best known for founding the Ethical Culture movement. Born in Alzey, Germany, Adler moved to the United States as a child. He was deeply influenced by his father, a rabbi, but ultimately diverged from traditional religious paths, seeking instead a more universal approach to ethics and spirituality. Adler studied at Columbia University and later in Germany, where he was exposed to the ideas of Immanuel Kant and other philosophers who emphasized rationalism and moral philosophy. In 1876, Adler delivered a sermon titled "The Religion of Duty," which marked the beginning of the Ethical Culture movement, advocating for ethics as a basis for human interaction and social progress, independent of religious doctrine. He emphasized the importance of individual responsibility, social justice, and moral action in daily life. Adler was also a professor at Columbia University and a social activist, contributing to various causes, including child labor reform, public education, and civil rights. His work in ethical philosophy and social reform had a profound impact on 19th and early 20th-century thought, and his legacy continues to influence discussions on secular ethics and moral responsibility.