Natural Law

"True law is right reason in agreement with nature, universal, consistent, everlasting, whose nature is to advocate duty by prescription and to deter wrongdoing by prohibition. Good men obey its prescriptions and prohibitions, but evil men disobey them. It is forbidden by God to alter this law, nor is it permissible to repeal any part of it, and it is impossible to abolish the whole of it. Neither the Senate nor the People can absolve us from obeying this law and we do not need to look outside ourselves for an expounder or interpreter of this law. There will not be one law at Rome and another law at Athens. There is now and will be forever one law, valid for all peoples and all times. And there will be one master and ruler for all of us in common, God, who is the author of this law, its promulgator, and enforcing judge. Whoever does not obey this law is trying to escape himself and to deny his nature as a human being. By this very fact, he will suffer the greatest penalties, even if he should somehow escape conventional punishments."
--Cicero’s definition of natural law from his book, On the Republic, published in 51 BC