The Marquis de Sade, born Donatien Alphonse François in 1740, was a French writer and philosopher known for his controversial works that explored themes of sexuality, freedom, and morality. His writings often depicted explicit sexual content and challenged societal norms, leading to his imprisonment and exile. Sade's most famous works include Justine and 120 Days of Sodom, which delve into the darker aspects of human nature. His ideas contributed to discussions about libertinism and the nature of desire, influencing later thinkers and writers, including Friedrich Nietzsche and Sigmund Freud.