One of the great Americans of our age, David Horowitz, died on Tuesday at the age of 86.

David Horowitz was one of the towering intellects and most perceptive thinkers of the late twentieth century and early twenty-first; he was also a man of unusual courage and remarkable vision. Though few people today realize it, David Horowitz was also one of the most influential people of our time, as he was one of the first leftists of any prominence to leave the leftist ranks and become a stalwart warrior for freedom.

Multitudes followed in his wake, often without realizing who it was who had blazed the trail for them. We are all in his debt not only for blazing that trial, but for the fact that after he established himself as a voice for freedom, sound values, and patriotism, David Horowitz spearheaded efforts to seize the intellectual and moral initiative from the left, and to articulate a vision for an America that really is the land of the free and the home of the brave.

After decades of the left’s cultural hegemony, David Horowitz played a massive role in establishing a large-scale movement of American patriots who refused to accept the claims of self-anointed “progressives” that their victory was inevitable, that they were on the right side of history, and that surrender was wiser than resistance. Today, that movement is broad-based, and one of its foremost exponents is in the Oval Office. Trump himself called Horowitz his “great friend.”

Stephen Miller, one of Donald Trump’s key advisers, was in his college days the president of the Duke chapter of David Horowitz’s Students for Academic Freedom; Miller’s uncompromising, unapologetic and deeply informed response to the left’s propaganda machine (that is, the establishment media) is redolent of Horowitz’s influence.

Even just a few years ago, Miller’s robustly pugnacious approach to the media propagandists would have been unthinkable. It was taken for granted that American conservatives let the left define the parameters of the public discourse and control the debate over any controverted issue. If the left denounced any voice for freedom on the right, which it did on a regular basis, establishment conservatives fell dutifully into line and denounced the target themselves.

These establishment conservatives were ignorant of or indifferent to the fact that Saul Alinsky, a man who had been a socialist activist like David Horowitz but who had never heeded the better angels of his nature and broken with the left, taught that radicals could defeat their foes by isolating a target, demonizing and destroying that target, and then proceeding onto the next target by first denouncing him for associating with the first target.

David Horowitz not only refused to play along with this game; he broke its power. At the David Horowitz Freedom Center’s flagship publication, Front Page Magazine, he did not let the left set the agenda; instead, he set his own. He didn’t shun figures who enunciated unpopular truths that the left wanted desperately to conceal; instead, he gave them a platform. He articulated an American conservatism that was not defensive, not reactive, not imitative of the left, but providing a vision for our nation’s future that is a genuine alternative to what the left has forced upon Americans for so long, and which preserves and strengthens what has made our nation great.

Nowadays, when patriots seek out pundits and political analysts who articulate what they themselves want for our country, and they encounter a strong and self-assured patriotic movement, this is to a great degree the fruit of the tireless labors of David Horowitz. When he and his longtime friend and colleague Peter Collier left Ramparts magazine, which was at the vanguard of the leftist movement in the late 1960s, and embraced the patriotism and love for freedom they had previously fought so energetically against, the American left lost two of its foremost thinkers; it has never recovered.

If free people prevail in this great struggle in which we are now engaged, and if an honest history of our turbulent age is someday written, David Horowitz will stand as one of those who shone forth most brightly when the darkness seemed all-pervasive and invincible.

It has been an immense honor for me personally to have known David for twenty years, and to have fought for freedom alongside him as part of the David Horowitz Freedom Center. At the Center, we are now determined to continue David’s fight for freedom and to keep on carrying the torch for freedom that he lit, until we prevail. May his memory be eternal.