Few people today, in the first years of the twenty-first century, have any knowledge or awareness of the concept of the law of nature or natural law in its relation to morality, law, or politics. Even lawyers know little or nothing about it unless their legal education happens to have included some instruction in the history and philosophy of law. If asked today what the law of nature means, most people would be likely to answer that it probably refers to causal order and invariable regularities in the phenomena of physical and biological nature that scientists have established or discovered, such as the laws of gravity, Boyle's law, or the double-helix structure of the DNA molecule. This is not, however, what it signifies in the history of Western thought. Looked at in this long temporal context and described in the very largest sense, the law of nature was an idealistic concept founded on the philosophical and religious assumption that nature and the universe as a divine creation of the eternal God are mindful of mankind and repositories of purpose, norms, and meanings based on right reason that include the principles of morality for human beings. Regarded in this light, the concept of a moral law of nature, which originated in classical Greek philosophy, occupied a dominant position in reflection on law, ethics, and politics for over two thousand years. During this period it was discussed by innumerable theologians, jurists, and philosophers, including some of the greatest minds, and was understood by many thinkers to constitute both a standard of legal justice and a moral standard for human actions. The decline of this concept, which began in the later eighteenth century and continued thereafter, was due to a number of factors: to the development of skepticism, empiricism, and utilitarianism, which questioned or denied the existence of a moral law of nature; to the displacement in legal thought of the abstract rationalism associated with the concept of natural law by a historical jurisprudence that looked upon law as a product of historical evolution and the collective social life of peoples and nations; and finally to the growth of legal positivism, philosophical naturalism, and moral relativism. In the present age, a belief in the law of nature has largely disappeared. While by no means extinct, it has ceased to be a significant influence in legal, political, and moral philosophy and survives mainly among Catholic thinkers and in Catholic philosophy and theology, which continue to uphold it as a moral guide. To some extent, what has taken its place in today's world is the current belief in human rights.