Isabel Paterson (January 22, 1886, – January 10, 1961) was a Canadian-American journalist, novelist, political philosopher, and a leading literary critic of her day. Along with Rose Wilder Lane and Ayn Rand, who both acknowledged an intellectual debt to Paterson, she is one of the three founding mothers of American libertarianism. Paterson's best-known work, her 1943 book The God of the Machine, a treatise on political philosophy, economics, and history, reached conclusions and espoused beliefs that many libertarians credit as a foundation of their philosophy. Her biographer Stephen D. Cox (2004) believes Paterson is the "earliest progenitor of libertarianism as we know it today." Ayn Rand wrote in a letter in the 1940s that The God of the Machine "does for capitalism what Das Kapital does for the Reds and what the Bible did for Christianity."