The secularisation of Natural Law began with the advent of the Reformation in Europe and the consequent decline of the Roman Catholic Church. This essentially resulted in Protestant theorists developing their own theories on natural law that were not based on papal teachings. Natural law doctrines faced further decline throughout the 18th century and into the 19th century where emphasis was placed on the notions of State power and State coercion. This era also saw a rise in the positivists approach to jurisprudential theories which were promoted by Jeremy Bentham and John Austin. Such jurists sought to separate the notions of what law is as opposed to what the law ought to be. The concepts of morality and law should be kept apart and the principles of Natural Law should belong more to the former than the latter .The 20th century saw a rebirth of Natural Law approaches to the study of law. To the forefront was the notion that there must be a higher set of principles (as distinct from positive law) which must satisfy natural law theories if law was to be regarded as valid. This revival was the result of a number of historical occurrences – Nazism (whose acts were based on Nazi laws); the development of nuclear weapons and other weapons of mass destruction; the general decline of social and economic stability worldwide.