"If men through fear, fraud or mistake, should in terms renounce and give up any essential natural right, the eternal law of reason and the great end of society, would absolutely vacate such renunciation; the right to freedom being the gift of God Almighty, it is not in the power of Man to alienate this gift, and voluntarily become a slave."
-- Samuel Adams, Rights of the Colonists, 1772
“There is a true law, a right reason, conformable to nature, universal, unchangeable, eternal, whose commands urge us to duty, and whose prohibitions restrain us from evil.”
-- Cicero, De Re Publica, Book III
"Those rights, then, which God and nature have established, and are therefore called natural rights, such as are life and liberty, need not the aid of human laws to be more effectually invested in every man than they are; neither do they receive any additional strength when declared by the municipal laws to be inviolable. On the contrary, no human legislation has power to abridge or destroy them, unless the owner himself commit some act that amounts to forfeiture."
-- William Blackstone
"Human law is law only by virtue of its accordance with right reason; and thus it is manifest that it flows from the eternal law. And in so far as it deviates from right reason it is called an unjust law; in such case it is no law at all, but rather a species of violence."
-- Thomas Aquinas, Summa theologiae, Ia-Ilae, q. xciii, art. 3, ad 2m.
"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness. That to secure these rights, governments are instituted among men..."
-- The Declaration of Independence