"Can be read online for free. Sophocles' "Antigone" (~442 BC) is the first literary piece in Western history that contains an argument in favor of natural law. Antigone resists Creon's law forbidding the burial of her brother, on the grounds that she is serving the law of the gods, which is greater than human law."
"Maritain and his wife RaÔssa made a pact in 1904 to jointly commit suicide if they didn't find meaning in life. They both converted to Roman Catholicism in 1906. Jacques Maritain is now considered the most important natural law theorist of the 20th century."