Jefferson did not write the Declaration in isolation. He named his sources in 1825 in a letter to Henry Lee: Aristotle, Cicero, Locke, Sidney. He said the Declaration aimed to place before mankind the common sense of the subject, not to invent new principles or new arguments. This episode traces each of those sources to the specific documents, confirms where they survive, and connects them to the language Jefferson used.
In 1825, forty-nine years after the Declaration was signed, Jefferson wrote to Henry Lee explaining what he had intended. The letter is at Founders Online. It is the primary source for understanding Jefferson own account of his intellectual sources and his purpose.
I did not consider it as any part of my charge to invent new ideas altogether, and to offer no sentiment which had ever been expressed before. Not to find out new principles, or new arguments, never before thought of, not merely to say things which had never been said before; but to place before mankind the common sense of the subject, in terms so plain and firm as to command their assent, and to justify ourselves in the independent stand we are compelled to take. Neither aiming at originality of principle or sentiment, nor yet copied from any particular and previous writing, it was intended to be an expression of the American mind, and to give to that expression the proper tone and spirit called for by the occasion. All its authority rests then on the harmonizing sentiments of the day, whether expressed in conversation, in letters, printed essays, or in the elementary books of public right, as Aristotle, Cicero, Locke, Sidney, etc.
The phrase elementary books of public right is the key. Jefferson was not apologizing for borrowing. He was stating the method: the Declaration was meant to express what educated colonists already believed, grounded in a tradition of political philosophy that ran from ancient Rome through seventeenth-century England to the Virginia Convention of 1776. The sources he named are all confirmable and all in institutional archives.
John Locke published Two Treatises of Government in 1689. The Second Treatise established the philosophical framework Jefferson drew on directly. Locke argued that all people are born free and equal, possess natural rights to life, liberty, and property that no government can legitimately take without consent, and that governments which violate these rights may be altered or abolished by the people. The Second Treatise is confirmed at the Online Library of Liberty, full text, public domain.
To understand political power right, and derive it from its original, we must consider, what state all men are naturally in, and that is, a state of perfect freedom to order their actions, and dispose of their possessions and persons, as they think fit, within the bounds of the law of nature, without asking leave, or depending upon the will of any other man.
The connection to the Declaration is direct. Locke named the foundational triad life, liberty, and estate (property). Jefferson changed property to the pursuit of happiness, a deliberate substitution. Locke established that governments derive their just powers from the consent of the governed, that when a government becomes destructive of the ends for which it was instituted the people have a right to alter or abolish it, and that this right is not rebellion but the exercise of a higher law. Every one of these ideas appears in the Declaration. Jefferson was not paraphrasing Locke. He was expressing what he and Locke both understood to be self-evident.
Algernon Sidney was executed in 1683 for alleged treason against Charles II. The primary evidence against him was his unpublished manuscript, Discourses Concerning Government, published posthumously in 1698. Sidney argued that governments exist to serve the people, that sovereignty ultimately resides in the people rather than the monarch, and that resistance to tyranny is not rebellion but the exercise of a natural right. Jefferson named Sidney alongside Locke in his 1825 letter to Henry Lee.
That which is not just, is not Law; and that which is not Law, ought not to be obeyed.
Sidney was widely read in the colonies. John Adams called him one of the most important political theorists in the republican tradition. The Discourses Concerning Government were cited by colonial leaders in the arguments leading up to independence. The argument that unjust laws carry no obligation of obedience is precisely the argument the Declaration makes in its list of grievances against the Crown. Sidney was executed for writing what Jefferson published as a founding document.
George Mason drafted the Virginia Declaration of Rights in May and June 1776. It was adopted by the Virginia Convention on June 12, 1776, twenty-two days before Jefferson completed his draft of the Declaration of Independence. Jefferson had a copy. The structural and verbal parallels are direct and deliberate. The Virginia Declaration is confirmed at Yale Avalon and at the Library of Congress.
That all men are by nature equally free and independent and have certain inherent rights, of which, when they enter into a state of society, they cannot, by any compact, deprive or divest their posterity; namely, the enjoyment of life and liberty, with the means of acquiring and possessing property, and pursuing and obtaining happiness and safety.
The happiness phrasing, often attributed solely to Jefferson as a departure from Locke, was already in Mason. Mason wrote pursuing and obtaining happiness and safety. Jefferson compressed and elevated it to the pursuit of Happiness. The Virginia Declaration also established that all government authority is derived from the people, that a majority of the community has the right to reform or alter their government, and that the freedom of the press is one of the great bulwarks of liberty. Jefferson synthesized Mason, Locke, and Sidney into a document intended not for Virginia alone but for all mankind.
Jefferson told Henry Lee that the Declaration was neither an original work nor a copy of any particular previous writing. It was a synthesis. He took the natural rights framework from Locke, the republican theory of resistance from Sidney, the specific language of equality and happiness from Mason, and the constitutional argument about parliamentary overreach from a century of colonial political writing. He assembled these into a document that was simultaneously philosophically grounded, legally argued, and emotionally resonant.
The Declaration is not weaker for having sources. It is stronger. The authority Jefferson claimed for it rested not on his individual genius but on the harmonizing sentiments of the day as he put it, the accumulated weight of a tradition that stretched back through two centuries of English constitutional thought and further through the Roman republic. When he wrote that these truths were self-evident, he meant that they were self-evident to anyone educated in this tradition. The Declaration was written for people who had read Locke and Sidney, who knew the Virginia Declaration, and who understood what was being claimed and why it mattered.
This was the object of the Declaration of Independence. Not to find out new principles, or new arguments, never before thought of, not merely to say things which had never been said before; but to place before mankind the common sense of the subject.
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