Two of the most famous early socialist thinkers were Robert Owen and Henri de Saint-Simon. Owen was a Welsh manufacturer who lived in the 18th and 19th centuries and was an influential advocate of utopian socialism. He was involved in community experiments on both sides of the Atlantic Ocean. Saint-Simon, whose life also straddled the 18th and 19th centuries, was born into a poor aristocratic French family. He became a social theorist and was one of the founders of Christian socialism, a mid-19th-century movement of Christian activists who sought to create social programs to address the plight of the poor.