Most people who know "I Can" could hum the piano hook in a second. It's the little tune half the planet learned a few bars of as a child. That hook is Beethoven. Nas's biggest single on the pop chart is sitting on top of "Für Elise."

Nas — "I Can" (official video)

Watch the video and a child plays the line on a piano, so you get the song and the source in the same breath. Some listeners treat that overlap as a confession. They love Beethoven and the long Romantic line behind him, the sweeping, heartbroken piano writing, and they also love Nas, and they say the second part quietly, as if the two things sit on opposite sides of a wall. There's no wall. The two worlds already overlap, and they've been overlapping for forty years.

Hip-hop learned its trade, in part, from the classical canon and everyone in its neighborhood. For about forty years now, rap producers have quietly raided that catalogue for the best tunes in the building, and Beethoven is right at the top of the pile. The surprise isn't that it happens. It's how often the song you already love turns out to be one of them.

The cleanest example is one of the biggest rap singles of its era

Nas recorded "I Can" in 2002 and put it out as a single in February 2003. That recognizable piano line running under the whole track is "Für Elise," the Beethoven piano miniature, carrying both the main melody and the harmony.

The producer Salaam Remi built the beat on it, then laid the drums from The Honey Drippers' "Impeach the President" on top, which is one of the most sampled breaks in the genre, a 1973 funk record that's turned up in 800-plus songs. So the foundation of "I Can" is a Beethoven piano piece and a 1970s funk drum break, welded together.

The Honey Drippers — "Impeach the President" (the drum break under "I Can")

"I Can" reached No. 12 on the Billboard Hot 100, the highest a Nas single has ever climbed with him as the lead artist.

His biggest moment on the pop chart is built on Beethoven.

Beethoven literally topped the American pop chart in 1976

The borrowing isn't a recent stunt born of running out of ideas, and the proof is that Beethoven himself once held the No. 1 single in the country. In 1976, an instrumental called "A Fifth of Beethoven" reached the top of the Billboard Hot 100.

Walter Murphy — "A Fifth of Beethoven" (1976)

Walter Murphy took the first movement of Beethoven's Symphony No. 5, the four notes everyone on Earth can sing, and turned it into a disco record. It went to the top of the American singles chart on October 9, 1976, and it later turned up on the "Saturday Night Fever" soundtrack, which is about as deep into mainstream pop culture as music gets. Rap and dance tracks have since reached back through that disco version to Beethoven's Fifth, which means the path runs concert hall to disco floor to sampler, with the same four notes surviving every step.

For a week in 1976, Beethoven's Fifth was the most popular single in the United States. The man couldn't have charted higher if he'd recorded it himself, and that was nearly fifty years ago. A producer putting a Beethoven miniature under a Nas verse in 2002 was working a seam the charts had already mined for decades.

Two ends of one long conversation

So when you love a great Romantic concerto and a sharp Nas record on the same afternoon, you aren't crossing a line. You're listening to two ends of one long conversation. The producers know the canon. They've always known the canon. They go to it for the same reason the concert halls do, because the tunes are better than the ones most people can write from scratch.

Both "I Can" and the chart-topping disco "Fifth" lead straight back to one composer, which makes Beethoven the obvious place to go and hear the raw material with no beat on top.

The Essential Classics Beethoven collection below is the deep version of what those producers were borrowing: the symphonies, the sonatas, the piano writing, all the way down. The four-note opening of the Fifth that became a No. 1 single, and the piano world that "Für Elise" comes from, both sit in that collection in their original form, full orchestra and solo keyboard, nothing sampled, nothing sped up.

Best of Beethoven — Essential Classics

Put it on and you start hearing the joins everywhere, the bits a producer would loop, the four bars worth lifting. That's exactly why the old music never went out of fashion. The next time a Nas hook makes you turn the volume up, listen under it. There's a decent chance a long-dead composer got there first.