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America’s First Constitutions and Declarations of Rights
complete isolation. ‘‘A man alone,’’ it is said, ‘‘is either a saint or a devil,’’
and not of this world.
Aristotle was part of what is called the natural law tradition in Western thought, which began with the ancient Greeks. The idea of natural
law stems from the belief that there is a higher law governing political
rulers and the affairs of mankind which emanates from God. This higher
law, said Aristotle, is knowable through reason. St. Thomas Aquinas, the
thirteenth-century theologian who adapted Aristotle’s teachings to Christian beliefs, wrote that revelation, that is, God’s word as revealed through
scripture, supplemented reason as a source of understanding the natural law.
What, in substance, is the natural law? By natural law we mean those
principles which are inherent in man’s nature as a rational, moral, and
social being, and which cannot be casually ignored. The term is confusing at first because it suggests the laws of physical nature, such as the
laws of chemistry or physics. Natural law refers, however, not to physical
but to human nature. We mean by this term not law which has been enacted, but the law which has been, or may be, discovered by man’s reason and experience. In essence, it is a system of ethics for governing the
political and legal affairs of man. It insists that there are universal truths,
such as justice, and that such truths are knowable through reason and
revelation; and that to violate them is to contravene the natural law. In
a famous passage in De Republica, Cicero described the natural law as
‘‘true law’’:
True law is right reason in agreement with Nature; it is of universal application, unchanging and everlasting; it summons to duty by its commands, and averts from wrongdoing by its prohibitions. And it does not
lay its commands or prohibitions upon good men in vain, though neither have any effect on the wicked. It is a sin to try to alter this law, nor
is it allowable to attempt to repeal any part of it, and it is impossible to
abolish it entirely. We cannot be freed from its obligations by the Senate
or people, and we need not look outside ourselves for an expounder or
interpreter of it. And there will not be different laws at Rome and at Athens, or different laws now and in the future, but one external and unchangeable law will be valid for all nations and for all times, and there