During the political upheavals of the 17th century, when the first libertarian agenda developed, the most influential case for natural rights came from the pen of scholar John Locke.

He expressed the radical view that government is morally obliged to serve people by protecting life, liberty and property. He explained the principle of checks and balances to limit government power. He favored representative government and a rule of law. He denounced tyranny. He insisted that when government violates individual rights, people may legitimately rebel.

These views were most fully expressed in Locke’s famous Second Treatise Concerning Civil Government, and they were so radical that he never dared sign his name to it. He acknowledged authorship only in his will. Locke’s writings did much to inspire the libertarian ideals of the American Revolution. This, in turn, set an example which inspired people throughout Europe, Latin America and Asia.

Thomas Jefferson ranked Locke, along with Locke’s compatriot Algernon Sidney, as the most important thinkers on liberty. Locke helped inspire Thomas Paine’s radical ideas about revolution. Locke fired up George Mason. From Locke, James Madison drew his most fundamental principles of liberty and government. Locke’s writings were part of Benjamin Franklin’s self-education, and John Adams believed that both girls and boys should learn about Locke. The French philosopher Voltaire called “Locke the man of the greatest wisdom. What he has not seen clearly, I despair of ever seeing.”

It seems incredible that Locke, of all people, could have influenced people around the world. When he set out to develop his ideas, he was an undistinguished Oxford scholar. He had brief experience with a failed diplomatic mission. He was a physician who long lacked traditional credentials and had just one patient. His first major work wasn’t published until he was 57. He was distracted by asthma and other chronic ailments.

There was little in Locke’s appearance to suggest greatness. He was tall and thin. According to biographer Maurice Cranston, he had a “long face, large nose, full lips and soft, melancholy eyes.” Although he had a love affair which “robbed me of the use of my reason,” he died a bachelor.

But some notable contemporaries thought highly of Locke. Mathematician and physicist Isaac Newton cherished his company. Locke helped Quaker William Penn restore his good name when he was a political fugitive, as Penn had arranged a pardon for Locke when he had been a political fugitive. Locke was described by the famous English physician Dr. Thomas Sydenham as “a man whom, in the acuteness of his intellect, in the steadiness of his judgement, in the simplicity, that is, in the excellence of his manners, I confidently declare to have, amongst the men of our time, few equals and no superiors.”

John Locke was born in Somerset, England, August 29, 1632. He was the eldest son of Agnes Keene, daughter of a small-town tanner; and John Locke, an impecunious Puritan lawyer who served as a clerk for justices of the peace.

Locke was 17 when Parliamentary forces hanged King Charles I, ushering in Oliver Cromwell’s military dictatorship. In 1652, after graduating from prestigious Westminister School, Locke won a scholarship to Christ Church, Oxford University which trained men mainly for the clergy. In November 1665, as a result of his Oxford connections, Locke went on a diplomatic mission in Brandenburg. The experience was a revelation because Brandenburg had a policy of toleration for Catholics, Calvinists and Lutherans, and there was peace.

During the summer of 1666, the rich and influential Anthony Ashley Cooper—also known as the Third Earl of Shaftsbury—visited Oxford where he met Locke who was then studying medicine. Cooper, a defender of religious toleration (except for Catholics), suffered from a liver cyst which threatened to become swollen with infection. Cooper asked Locke to be his personal physician. Accordingly, Locke moved into a room at Cooper’s Exeter House mansion, Westminister, London. Shaftsbury’s liver infection worsened, and Locke supervised successful treatment in 1668. He had a barber-surgeon remove inflamed tissues and insert a silver tube through the stomach to drain fluids which might spread infection. Astonishingly for that age when medical practice often did more harm than good, the patient recovered.

Shaftsbury retained Locke to analyze toleration, education, trade and other issues, and among other things he opposed government efforts to restrict interest rates. Locke was in the thick of just about everything Shaftsbury did. Shaftsbury formed the Whig party, and Locke carried on a correspondence to help influence Parliamentary elections. Shaftsbury was imprisoned for a year in the Tower of London, then he helped pass the Habeas Corpus Act (1679) which made it unlawful for government to detain a person without filing formal charges. The Habeas Corpus Act also specified that an individual could not be put on trial for the same charge twice. Shaftsbury pushed “exclusion bills” aimed at preventing the king’s Catholic brother from royal succession.

In March 1681, Charles II dissolved Parliament, and it soon became clear that he didn’t intend to summon Parliament again. Consequently, the only way to stop Stuart absolutism was rebellion. Shaftsbury was the king’s most dangerous opponent, and Locke was at his side.

Locke prepared an attack on Robert Filmer’s Patriarcha, or The Natural Power of Kings Asserted (1680) which claimed that God sanctioned the absolute power of kings. Such an attack was risky since it could easily be prosecuted as an attack on King Charles II. Pamphleteer James Tyrrell, a friend whom Locke had met at Oxford, left unsigned his substantial attack on Filmer, Patriarcha Non Monarcha or The Patriarch Unmonarch’d; and Tyrrell had merely implied the right to rebel against tyrants. Algernon Sidney was hanged, in part, because the king’s agents discovered his manuscript for Discourses Concerning Government.

Locke worked in his bookshelf-lined room at Shaftsbury’s Exeter House, drawing on his experience with political action. He wrote one treatise which attacked Filmer’s doctrine. Locke denied Filmer’s claim that the Bible sanctioned tyrants and that parents had absolute authority over children. Locke wrote a second treatise which presented an epic case for liberty and the right of people to rebel against tyrants. While he drew his principles substantially from Tyrrell, he pushed them to their radical conclusions: namely, an explicit attack on slavery and a defense of revolution.

As Charles II intensified his campaign against rebels, Shaftsbury fled to Holland in November 1682 and died there two months later. On July 21, 1683, Locke might well have seen the powers that be at Oxford University burn books considered dangerous in the Bodleian Quadrangle. It was England’s last book burning. Locke owned some of the outlawed titles. When he feared his rooms would be searched, he initially hid his draft of the two treatises with Tyrrell. Locke moved out of Oxford, checked on country property he had inherited from his father, then fled to Rotterdam September 7th.

The English government tried to have Locke extradited for trial and presumably hanging. He moved into one Egbertus Veen’s Amsterdam house and assumed the name “Dr. van der Linden.” He signed letters as “Lamy” or “Dr. Lynne.” Anticipating that the government might intercept mail, Locke protected friends by referring to them with numbers or false names. He told people he was in Holland because he enjoyed the local beer.

Meanwhile, Charles II died in February 1685, and his brother became King James II who began promoting Catholicism in England. He defied Parliament. He replaced Anglican Church officials and sheriffs with Catholics. He staffed the army with Catholic officers. All this was a threat to English people who cherished their independence from the Pope as well as from Catholic kings like Louis XIV of France.

In Holland, Locke worked on his philosophical masterpiece, An Essay Concerning Human Understanding which urged people to base their convictions on observation and reason. He also worked on a “letter” advocating religious toleration except for atheists (who wouldn’t swear legally-binding oaths) and Catholics (loyal to a foreign power).

On June 10, 1688, James II announced the birth of a son, and suddenly there was the specter of a Catholic succession. This convinced Tories, as English defenders of royal absolutism were known, to embrace Whig ideas of rebellion. The Dutchman William of Orange, agreeing recognize the supremacy of Parliament, crossed the English Channel on November 5, 1688, and within a month, James II fled to France. This was the “Glorious Revolution” which helped secure Protestant succession and Parliamentary supremacy without violence.

Locke returned home, and during the next 12 months, his major works were published, and suddenly he was famous. Limborch published Locke’s Epistola de Tolerantia in Gouda, Holland May 1689—Locke wrote in Latin presumably to reach a European audience. The work was translated as A Letter Concerning Toleration and published in October 1689. Locke didn’t take religious toleration as far as his Quaker compatriot William Penn—Locke was concerned about the threat atheists and Catholics might pose to the social order—but he opposed persecution. He went beyond the Toleration Act (1689), specifically calling for toleration of Anabaptists, Independents, Presbyterians and Quakers.

“The Magistrate,” he declared, “ought not to forbid the Preaching or Professing of any Speculative Opinions in any Church, because they have no manner of relation to the Civil Rights of the Subjects. If a Roman Catholick believe that to be really the Body of Christ, which another man calls Bread, he does no injury therby to his Neighbour. If a Jew do not believe the New Testament to be the Word of God, he does not thereby alter any thing in mens Civil Rights. If a Heathen doubt of both Testaments, he is not therefore to be punished as a pernicious Citizen.” Locke’s Letter brought replies, and he wrote two further letters in 1690 and 1692.

Locke’s two treatises on government were published in October 1689 with a 1690 date on the title page. While later philosophers have belittled it because Locke based his thinking on archaic notions about a “state of nature,” his bedrock principles endure. He was concerned about arbitrary power, which “becomes Tyranny, whether those that thus use it are one or many.” He defended the natural law tradition whose glorious lineage goes back centuries to the ancient Jews: the tradition that rulers cannot legitimately do anything they want, because there are moral laws applying to everyone.

“Reason, which is that Law,” Locke declared, “teaches all Mankind, who would but consult it, that being all equal and independent, no one ought to harm another in his Life, Health, Liberty, or Possessions.” Locke envisioned a rule of law: “have a standing Rule to live by, common to every one of that “Society, and made by the Legislative Power erected in it; A Liberty to follow my own Will in all things, where the Rule prescribes not; and not to be subject to the inconstant, uncertain, unknown, Arbitrary Will of another Man.”

Locke established that private property is absolutely essential for liberty: “every Man has a Property in his own Person. This no Body has any Right to but himself. The Labour of his Body, and the Work of his Hands, we may say, are properly his.” He continues: “The great and chief end therefore, of Mens uniting into Commonwealths, and putting themselves under Government, is the Preservation of their Property.”

Locke believed people legitimately turned common property into private property by mixing their labor with it, improving it. Marxists liked to claim this meant Locke embraced the labor theory of value, but he was talking about the basis of ownership rather than value.

He insisted that people, not rulers, are sovereign. Government, Locke wrote, “can never have a Power to take to themselves the whole or any part of the Subjects Property, without their own consent. For this would be in effect to leave them no Property at all.” He makes his point even more explicit: rulers “must not raise Taxes on the Property of the People, without the Consent of the People, given by themselves, or their Deputies.”

Then Locke affirmed an explicit right to revolution: “whenever the Legislators endeavor to take away, and destroy the Property of the People, or to reduce them to Slavery under Arbitrary Power, they put themselves into a state of War with the People, who are thereupon absolved from any farther Obedience, and are left to the common Refuge, which God hath provided for all Men, against Force and Violence. Whensoever therefore the Legislative shall transgress this fundamental Rule of Society; and either by Ambition, Fear, Folly or Corruption, endeavor to grasp themselves, or put into the hands of any other an Absolute Power over the Lives, Liberties, and Estates of the People; By this breach of Trust they forfeit the Power, the People had put into their hands, for quite contrary ends, and it devolves to the People, who have a Right to resume their original Liberty.”

To help assure his anonymity, he dealt with the printer through his friend Edward Clarke who might have been the only person to know the author’s identity. Locke denied rumors that he was the author, and he begged his friends to keep their speculations to themselves. He cut off those like James Tyrrell who persisted in talking about Locke’s authorship. Locke destroyed the original manuscripts and all references to the work in his writings. His only written acknowledgement of authorship was in an addition to his will, signed a couple weeks before he died. Ironically, the two treatises caused hardly a stir during his life. Nobody bothered to attack it, as happened with Locke’s writings on religion.

Locke’s byline did appear with An Essay Concerning Human Understanding, published December 1689, and it established him as England’s leading philosopher. He challenged the traditional doctrine that learning consisted entirely of reading ancient texts and absorbing religious dogmas. He maintained that understanding the world required observation. He encouraged people to think for themselves. He urged that reason be the guide. This book became one of the most widely reprinted and influential works on philosophy.

In 1693, Locke published Some Thoughts Concerning Education which offered many ideas as revolutionary now as they were then. He declared education is for liberty. He believed that setting a personal example is the most effective way to teach moral standards and fundamental skills, which is why he recommended homeschooling. He objected to government schools. He urged parents to nurture the unique genius of each child.

Francis and Damaris Masham invited Locke to spend his last years at Oates, their red brick Gothic-style manor house in North Essex, about 25 miles from London. He had a ground floor bedroom and an adjoining study with most of his 5,000-volume library. He insisted on paying: a pound per week for his servant and himself, plus a shilling a week for his horse.

Locke gradually became infirm. He lost most of his hearing. His legs swelled up. By October 1704, he could hardly arise to dress. Around 3:00 in the afternoon, Saturday, October 28th, he was sitting in his study with Lady Masham. Suddenly, he brought his hands to his face, shut his eyes and died. He was 72. He was buried in the High Laver churchyard.

During the 1720s, the English radical writers John Trenchard and Thomas Gordon popularized Locke’s political ideas in Cato’s Letters, a popular series of essays published in London newspapers, and these had the most direct impact on American thinkers. Locke’s influence was most apparent in the Declaration of Independence, the constitutional separation of powers and the Bill of Rights.

Meanwhile, Voltaire, witty critic of religious intolerance, had promoted Locke’s ideas in France. Ideas about the separation of powers were expanded by Baron de Montesquieu. Locke’s doctrine of natural rights appeared at the outset of the French Revolution, in the Declaration of the Rights of Man, but his belief in the separation of powers and the sanctity of private property never took hold there. Hence, the Reign of Terror.

Then Locke virtually vanished from intellectual debates. A conservative reaction engulfed Europe as people associated talk about natural rights with rebellion and Napoleon’s wars. In England, Utilitarian philosopher Jeremy Bentham ridiculed natural rights, proposing that public policy be determined by the greatest-happiness-for-the-greatest-number principle. But both conservatives and Utilitarians proved intellectually helpless when governments demanded more power to rob, jail and even murder people in the name of doing good.

In recent decades, some thinkers like novelist-philosopher Ayn Rand and economist Murray Rothbard revived a compelling moral case for liberty based on natural rights. They provided a meaningful moral standard for determining whether laws are just. They inspired millions as they sounded the battle cry that people everywhere are born with equal rights to life, liberty and property. They stood on the shoulders of John Locke.