Overton was one of the Levellers who, during the English Civil War, were among the very first to articulate the early ideas of liberalism.

An Arrow Against All Tyrants

To every individual in nature is given an individual property by nature not to be invaded or usurped by any. For every one, as he is himself, so he has a self-​propriety, else could he not be himself; and of this no second may presume to deprive any of without manifest violation and affront to the very principles of nature and of the rules of equity and justice between man and man. Mine and thine cannot be, except this be. No man has power over my rights and liberties, and I over no man’s. I may be but an individual, enjoy my self and my self-​propriety and may right myself no more than my self, or presume any further; if I do, I am an encroacher and an invader upon another man’s right — to which I have no right. For by natural birth all men are equally and alike born to like propriety, liberty and freedom; and as we are delivered of God by the hand of nature into this world, every one with a natural, innate freedom and propriety — as it were writ in the table of every man’s heart, never to be obliterated — even so are we to live, everyone equally and alike to enjoy his birthright and privilege; even all whereof God by nature has made him free. And this by nature everyone’s desire aims at and requires; for no man naturally would be befooled of his liberty by his neighbour’s craft or enslaved by his neighbour’s might. For it is nature’s instinct to preserve itself from all things hurtful and obnoxious; and this in nature is granted of all to be most reasonable, equal and just: not to be rooted out of the kind, even of equal duration with the creature. And from this fountain or root all just human powers take their original — not immediately from God (as kings usually plead their prerogative) but mediately by the hand of nature, as from the represented to the representers. For originally God has implanted them in the creature, and from the creature those powers immediately proceed and no further. And no more may be communicated than stands for the better being, weal, or safety thereof. And this is man’s prerogative and no further; so much and no more may be given or received thereof: even so much as is conducent to a better being, more safety and freedom, and no more. He that gives more, sins against his own flesh; and he that takes more is thief and robber to his kind — every man by nature being a king, priest and prophet in his own natural circuit and compass, whereof no second may partake but by deputation, commission, and free consent from him whose natural right and freedom it is.… For by nature we are the sons of Adam, and from him have legitimately derived a natural propriety, right and freedom, which only we require. And how in equity you can deny us we cannot see. It is but the just rights and prerogative of mankind (whereunto the people of England are heirs apparent as well as other nations) which we desire; and sure you will not deny it us, that we may be men and live like men. If you do, it will be as little safe for yourselves and posterity as for us and our posterity. For sir, look: what bondage, thraldom, or tyranny soever you settle upon us, you certainly, or your posterity will taste of the dregs. If by your present policy and (abused) might, you chance to ward it from yourselves in particular, yet your posterity — do what you can — will be liable to the hazard thereof. These selections have been excerpted from a letter written by Richard Overton, while a prisoner at Newgate, to Henry Marten, a member of the House of Commons, in protest of what he saw as tyranny.