"What is conservatism?" Abraham Lincoln once asked. "Is it not the adherence to the old and the tried, against the new and the untried?" It is that, and so much more.

Feb. 12,2009 marks the 200th anniversary of the birth of Lincoln, one of America's great statesmen. It's an important occasion for us to consider anew his legacy and importance for our nation and the cause of freedom.

That Lincoln is widely embraced today in American culture and society -- on both the left and the right -- reminds us that our 16th president has permanent resonance and meaning in our country, indeed, in the world. But what is that meaning?

In his Lyceum Address of 1838, the young state senator from Illinois wondered what posed the greatest threat to the perpetuation of our liberty. We were in possession of a great land, rich in resources, and living under political institutions conducing "to the ends of civil and religious liberty, than any of which the history of former times tells us."

At what point is the approach of danger to be expected? "If it ever reach us," Lincoln answered his own question, "it must spring up amongst us. If destruction be our lot, we must ourselves be its author and finisher. As a nation of freemen, we must live through all time, or die by suicide."

Already by the time of Lincoln's day, we had suffered much from the silent artillery of time. If we are to prevent the republic from falling, he warned, we must constantly shore up the foundations that maintain liberty.

How are we to do that? Lincoln's words, true then, speak to us just as much today:

"Let every American, every lover of liberty, every well wisher to his posterity, swear by the blood of the Revolution, never to violate in the least particular, the laws of the country; and never to tolerate their violation by others. As the patriots of '76 did to the support of the Declaration of Independence, so to the support of the Constitution and Laws, let every American pledge his life, his property, and his sacred honor."

Like any great historical figure, there is debate about Lincoln's place in our pantheon.

Liberals claim Lincoln as one of their own, as the father of the modern state, centralizing government and overcoming constitutional barriers to free America from the shackles of its outdated past. Such is the teaching of many mainstream historians.

Among conservatives, there has long been a bit of trepidation about Lincoln, mostly because we don't like the centralization and unlimited government of the modern state.

But those things come out of the transformation wrought by the progressive liberalism that rose up after the Civil War -- when progressive intellectuals looked to European thinkers for guidance -- and not from Lincoln, who took his guidance from the Constitution and the Declaration of Independence.

For us conservatives, while we have our debates -- and we will continue to have our debates -- when it comes to the refounding of America by modern liberalism, Lincoln is on our side: the side of fundamental equal rights of every individual grounded in human nature, of limited constitutional government grounded in the rule of law, of economic liberty grounded on the fruit of honest labor, and human liberty grounded on the idea that all men everywhere have the right to be free. There is no confusion on this.

As for me, I'll take my cue from Russell Kirk, the sage of Mecosta. He considered Lincoln "a conservative statesman of a high order" who, "knowing that there is a Truth above the advantage of the hour, argued from definition." Arguing from definition means arguing from principle. Kirk went on to say:

"He knew that what moved him was a power from without himself; and, having served God's will according to the light that was given him, he received the reward of the last full measure of devotion."

At Gettysburg, President Lincoln called for "a new birth of freedom," for the renewal of government of the people, by the people and for the people. This was not a call for constant change, remaking America over and over again from the ground up. His was a call to recover our principles, and to revive them in the context of the time.

In thinking of the future of America in the modern world, progressives then and now look ahead to open-ended possibilities. Lincoln first looked back to our beginnings for guidance and inspiration, back to America's founders. He was a great leader in difficult times of division and war, but his true statecraft is to be found in his articulation of our first principles as the only true guide in an unknowable future.

At a time when we're looking to reset our nation's compass, Lincoln points us toward timeless truths, "applicable to all men and all times."

"Our republican robe is soiled, and trailed in the dust. Let us repurify it," Lincoln said in his great speech at Peoria, Ill., in 1854, which my dear friend Lew Lehrman writes about so eloquently in his new book:

"Let us re-adopt the Declaration of Independence, and with it, the practices, and policy, which harmonize with it. Let north and south -- let all Americans -- let all lovers of liberty everywhere -- join in the great and good work. If we do this, we shall not only have saved the Union; but we shall have so saved it, as to make, and to keep it, forever worthy of the saving. We shall have so saved it, that the succeeding millions of free happy people, the world over, shall rise up, and call us blessed, to the latest generations."

It is right, then, that we honor Abraham Lincoln, and celebrate his conservative legacy of freedom.

Ed Feulner is president of The Heritage Foundation.