From the covenants of seventeenth-century England and colonial America to the doctrine of judicial review developed by Madison, Hamilton, and Marshall, the visible institutions of modern constitutionalism owe more to Christian traditions of covenant, jurisdictional pluralism, and Augustinian anthropology than is commonly recognized. 
Long before the separation of powers and judicial review were given written form, Greek philosophy, Roman law, Christian theology, and the medieval doctrine of paired jurisdictions laid the deeper architecture of constitutional government.