The great Abraham Lincoln historian Harry V. Jaffa, one of the great thinkers of his generation, has passed away at the age of 96.

Jaffa’s contribution as a philosophical historian inspired the work of countless conservatives today, especially those at the highly influential Claremont Institute. Hillsdale College president Larry P. Arnn, Civil War historian Allen Guelzo, and Justice Clarence Thomas are among the many conservatives that have drawn heavily from his ideas.

Jaffa and those who followed in his intellectual camp, often called “West Coast Straussians,” have juxtaposed their political philosophy, which flows from the timeless ideas of of the Founding Fathers, with some of the the most potent, and insidious ideas that have arisen in the last few centuries. Jaffa’s conservatism, couched in a longer Western tradition that included Christianity and Enlightenment thought, was a uniquely American philosophy. His career was dedicated to ensuring that the American political tradition, exemplified in his mind by the Founders and cemented by Lincoln, would remain at the cornerstone of American thought. To this end, Jaffa frequently found himself at odds, not only with the left, but with his fellow conservatives, whom he could be particularly hard on.

Jaffa worked briefly in party politics early in his career, acting as a speechwriter for the doomed Barry Goldwater presidential campaign of 1964. It was Jaffa who crafted among the most memorable of Goldwater lines, “Extremism in pursuit of liberty is no vice! And let me remind you also that moderation in defense of justice is no virtue!” This line, often mistakenly attributed to the Roman statesman, Cicero, drew the ire of Goldwater’s opponents and energized the great Arizona conservative’s most ardent supporters. Though Jaffa’s brief political career contributed one of the most famous phrases in modern politics, it was through his academic career that he made the most profound impact.

Some of Jaffa’s earliest works were strictly about philosophy, such as Thomism and Aristotelianism. But his two books on Abraham Lincoln—written nearly a half century apart—and numerous others on the American founding, were incredible examples of philosophy being linked directly to history. Jaffa’s book, Crisis of the House Divided, is an unsurpassed analysis of the 1858 Lincoln-Douglas debates that pitted Illinois Senator Stephen A. Douglas against Abraham Lincoln, launched Lincoln to the presidency, and changed the nation forever.

Jaffa not only grounded Lincoln’s philosophy in a comprehensive set of principles unlike any of his biographers before or since, but tied those principles to a truly unique, American conservatism. Taking cues from his mentor, Leo Strauss, Jaffa examined the philosophical underpinnings of the American political tradition, and tied it primarily to the principles of natural law proponents such as John Locke, Thomas Jefferson, and Lincoln. By placing the Declaration of Independence at the heart of the American political thought, Jaffa set himself apart from many on both the political left and right.

The progressive President Woodrow Wilson once said, “If you want to understand the real Declaration of Independence, do not repeat the preface.” However, Jaffa argued that the preface of the Declaration, especially “we hold these truths to be self-evident that all men are created equal,” defined the American political soul and American exceptionalism. Individual, natural rights stemming from nature and nature’s God, based on the principle of the equality are the basis of our liberties. Rights come from neither society nor government, they belong to all individuals and derive from natural equality of man.

Jaffa’s understanding of the axiomatic principles of the founding is perhaps best explained by Thomas Jefferson’s phrase that the “mass of mankind has not been born with saddles on their backs, nor a favored few booted and spurred, ready to ride them legitimately, by the grace of God.” Because human beings are in a fundamental sense created equal, no man has the right to rule others without their consent.

In an essay about the principles of James Madison, Jaffa tied the idea of natural human equality to the design of the Constitution and protection of individual rights.

Jaffa wrote:

Natural equality leads to the social contract which leads to majority rule. But majority rule is the means to implement the equal rights of all: all who have consented to be fellow citizens, and therefore have consented to majority rule. The problem, at this point, is to prevent the rule of the majority in the interest of all from degenerating into the rule of the majority in the interest of the majority–the tyranny of the majority. Hence the separation of powers, and the other devices of constitutionalism.

The structure of the Constitution, with it many checks on arbitrary power, were put in place to fundamentally protect individual rights while advancing the common good of all. According to Jaffa, this system must be viewed in light of the natural law philosophy that undergirded the work of the framers.

Jaffa understood the principles of the American founding to be “transhistorical”; truths about humanity that apply to all men in all times. The permanent truths so widely accepted at the time of the founding, expressed profoundly by Lincoln a generation later, clash harshly with the ideas that dominate among today’s intellectual elite and universities.

Harry Jaffa, often unbending in his views, provoked numerous intellectual fights with political opponents but also with many of his closest friends and allies. William F. Buckley once quipped, “If you think Harry Jaffa is hard to argue with, try agreeing with him.” Regardless of whether one agreed or disagreed with Jaffa, he was always able to push his allies and opponents into thinking more deeply about the position they defended.

Not contented with the mundane, day-to-day aspects of politics, Jaffa was focused on discovering and describing the essence of political philosophies. He especially wanted to get to the root of what conservatism truly is, and came to his own conclusion that it must be based on the unique set of principles passed down from the Founding Fathers. He wanted no less than a new birth of freedom in America and was ready to push and prod allies into going down the right course.

Jaffa’s ideas will continue to be advanced and debated by generations of Americans to come, and conservatives of all stripes owe him a profound debt of gratitude.