It’s remembered as a day chilled by “a Siberian wind knifing down Pennsylvania Avenue” and illuminated by “the dazzling combination of bright sunshine and deep snow.”

On Jan. 20, 1961, John F. Kennedy began his presidency with a speech at once soaring and solemn. Fifty years on, we have not heard an inaugural address like it. Tethered to its time and place, it still challenges with its ambition to harness realism to idealism, patriotism to service, national interest to universal aspiration.

Theodore Sorensen, the speech’s principal architect, was always modest about his own role, less so about the inaugural itself. “It certainly was not as good as Lincoln’s second or FDR’s first,” Sorensen wrote in his memoir, adding that Kennedy thought it not as good as Jefferson’s first.

By acknowledging what their joint product was not, Kennedy and Sorensen defined the historical company it still keeps.

A great speech includes lines so memorable that pedestrian orators eventually transform them into cliches. “Ask not what your country can do for you, ask what you can do for your country.” This muscular call for sacrifice has launched a thousand lesser speeches.

“Civility is not a sign of weakness” and “Let us never negotiate out of fear, but let us never fear to negotiate” — staple references whenever politics become particularly vicious.

“The torch has been passed to a new generation of Americans.” And the torch gets passed on again and again, whenever a younger politician is marking out generational territory.

It was a compact speech — at 1,355 words, it was less than twice the length of this column. Kennedy, wrote the historian Robert Dallek, insisted it be brief because “I don’t want people to think I’m a windbag.” He needn’t have worried.

Right and left still battle over Kennedy’s words. Were they a call for resolve before the communist threat (“we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, to assure the survival and the success of liberty”) or were they a plea for negotiation as the answer to nuclear annihilation?

Probably both. The classic realist’s declaration that “only when our arms are sufficient beyond doubt can we be certain beyond doubt that they will never be employed” was followed by this:

“But neither can two great and powerful groups of nations take comfort from our present course — both sides overburdened by the cost of modern weapons, both rightly alarmed by the steady spread of the deadly atom, yet both racing to alter that uncertain balance of terror that stays the hand of mankind’s final war.

“So let us begin anew.”

And so have we remained a nation forever in search of new beginnings, invoking, by turns, Lincoln or Kennedy to bless our fresh starts.

All writers take heart: Kennedy and Sorensen wrote and rewrote, often accepting changes proposed by friends. One fortunate fix came from John Kenneth Galbraith. The final address read: “United, there is little we cannot do in a host of cooperative ventures.” The original draft referred to “joint ventures,” which Galbraith thought sounded like a mining company.

They also took columnist Walter Lippmann’s suggestion, changing “enemy” to “adversary.” The less hostile word fit better with the speech’s wish that “a beachhead of cooperation may push back the jungle of suspicion” — a line the self-critical Sorensen saw as “a metaphorical stretch.”

And Kennedy advisers Harris Wofford and Louis Martin won the insertion of six words and helped change history.

In the original draft, Kennedy declared that the new generation for which he spoke was “unwilling to witness or permit the slow undoing of those human rights to which this nation has always been committed, and to which we are committed today.”

To which Wofford and Martin got Kennedy to add, “at home and around the world,” thus marrying the struggle for freedom abroad with the cause of domestic civil rights. There would be no turning back.

Perhaps I should acknowledge that I fell in love with this speech when I was young, purchasing a long-playing record of Kennedy addresses for 99 cents at the supermarket and listening to it over and over after Kennedy’s assassination.

You might say that I still hear its trumpet summoning us again. And when Kennedy said, “I do not believe that any of us would exchange places with any other people or any other generation,” I knew — millions of others felt this way too — that he was speaking for me.

E.J. Dionne’s e-mail address is ejdionne(at)washpost.com.