”Nixon By Nixon: In His Own Words” digs into more than 3,700 hours of recordings that captured practically everything the president said while in the Oval Office. (Courtesy of HBO)

If you didn’t know it already, you’re certainly going to know by the end of this week that the 40th anniversary of President Richard M. Nixon’s resignation is upon us.

Far be it from me to sit here in The Washington Post’s newsroom on a late, lonely weeknight in this brown-bricked, 1970s-era building at 1150 15th St. NW and dissuade anyone from one last round (for now) of Watergate nostalgia, which television has been capably churning out for the last couple of years, since the 40th anniversary of the bungled June 1972 break-in that started it all. Even Robert Redford got in on the action with “All the President’s Men Revisited,” which aired on Discovery last year.

The story still has great legs, doesn’t it?

The other night, there was a line of people around the block waiting to get in to hear Bob Woodward and Carl Bernstein reminisce about the scandal that profoundly altered Washington. By the time the 50th anniversary rolls around in 2024, The Post’s drab but still beloved building may well be gone — the newspaper changed hands last year, the building has been sold and The Post’s operations will relocate to an office building on K Street NW in 2016.

I tell you this only to steer you, without too much comment, to Peter Kunhardt’s simple and riveting “Nixon by Nixon: In His Own Words,” an HBO documentary airing Monday night. Though not as artfully constructed as Penny Lane’s excellent documentary “Our Nixon,” which aired last year on CNN, “Nixon by Nixon” is similarly judicious in its use of visuals and old footage.

But the real power here is in the audio. The subtitle (“in his own words”) refers to the 3,700 hours of tape recordings that captured practically everything Nixon said in his Oval Office and other locations in the White House, most often picked up in his phone calls. (It’s easy to get the impression here that being president involves nothing more than acting out one’s anger on the phone all day.)

Released bit by bit between Nixon’s death in 1994 and last August, the tapes are a trove of the nastiness and paranoia that will, unfortunately or otherwise, serve as history’s most complete portrait of who Nixon really was. We may never listen to them all, but Kunhardt’s film is adept at picking the choicest moments.

There’s no getting around it: As the tapes reflect, the president repeatedly told his closest confidants that Jews could never be trusted, that some Mexican Americans living in the United States were better than others (and he, especially, knew the difference), that women weren’t ready to be on the Supreme Court, that homosexuality was perhaps understandable but a scourge nonetheless.

The common slurs for all of these types of his fellow Americans roll out of his mouth with easy disdain. Nixon held a more specific and less abstract contempt for his perceived enemies, especially specific reporters and media outlets. That’s well represented here, too, as are moments in which Nixon’s propensity for committing crimes — or, at least, hypothetically wishing aloud that they could be committed, letting ambiguity fill in his blanks — is also brought into an alarming focus.

Whenever history begins to soften Nixon’s edges and admire his breakthroughs in foreign diplomacy, one need only to hit play again on the tapes and wait for the blood to boil — his or yours. Kunhardt’s film doesn’t only feature Nixon at his worst (there’s one sweet, short exchange when his daughter Julie calls up and suggests a family dinner that night at Trader Vic’s), but even in his moments of triumph or self-satisfaction, the recordings find him obsessed with his public image.

It seems as if we’ll be playing these tapes for at least another 40 years, maybe another 400. Perhaps Nixon was our Shakespeare. They’re still worth a listen.

To what end, you might ask. For what possible purpose in 2014?

Because they are astonishing and singular in their darkness.

Nixon by Nixon: In His Own Words

(75 minutes) premieres Monday

at 9 p.m. on HBO, with encores.