Prog-rock heroes Rush celebrated the 40th anniversary of their current lineup — Geddy Lee on bass and vocals, Alex Lifeson on guitar, and Neil Peart on drums — this year by embarking on an epic tour where they performed career-spanning shows packed with songs from across their massive discography. And while the concerts may be Rush’s last for the foreseeable future — “The days of us doing long tours are probably over,” Lee tells EW — combing their catalog for rarities and hits alike created some of the most memorable shows the band has played in years.

“It just felt great to play them,” Lee says of revisiting older tunes. “You put yourself back in the frame of mind you were when you wrote it. And even though it’s many years later, you’re playing it better because you’re better as a player. It has even more intensity.”

Rush capture the massive gigs — sequenced in reverse chronological order to amp up the nostalgic vibes — on R40, a live set out today culled from the tour’s two stops in the band’s hometown of Toronto. Lee and Lifeson sat down with EW to share behind-the-scenes stories from some of the collection’s songs, ranging from their unexpected smash “Tom Sawyer” to 1982 deep cut “Losing It.”

“Headlong Flight” (2012)

GEDDY LEE: That came from a bunch of jam sessions. Our original intention was that it was going to be instrumental.

ALEX LIFESON: I had my guitar tuned to E major, because we were just messing around, trying different things. The jam started out bluesy and developed into that.

GL: When you’ve had a long career it’s OK to borrow from yourself, because that’s sort of what style is. But you have to do it in a fresh way that brings something completely new. I’m particularly proud of that song, I think it’s one of the best we’ve ever written.

“Roll The Bones” (1991)

GL: We were looking for something that felt different and were trying to find a funk vibe — you know, a white Canadian funk vibe, not an actual real funk vibe. Then Neil came in with this crazy rap he’d written, which was very angular and not very rap-like rap.

AL: We didn’t want it to be too corny. We talked about getting someone else to do that rap, an actual legitimate rapper at the time.

GL: We looked at comedians, to just have fun with it. We talked about John Cleese at one point. In the end, none of those ideas stuck and we just decided to electronically de-tune my voice, with me doing the rap but sounding like some sort of cyborg. When we released it, some rock stations wouldn’t play it because it had a rap in it. There is really nothing rap about that song.

AL: It was an exercise in rhyme.

GL: [Neil] dug some of the rap stuff that was out there, and I think more than anything he loved the idea of street poetry, which is where rap was really born. He was just having fun with his own version of that.

“Losing It” (1982)

AL: It fit the thematic idea of [1982’s Signals].

GL: Neil had this lyric bout how tough it is when someone who has been at the top of their game starts to lose their ability to reproduce that. So we wrote this melodic, melancholy tune.

AL: [Violinist] Ben [Mink] was in the studio with us. We were messing around, playing Christmas carols and things like that.

GL: Ben went to town on it. He plays electric violin the way Jeff Beck plays guitar.

AL: I suggested [performing it in 2015] and the guys embraced it. We’d never played it live and it has such a particular character to it. We wanted to keep the show pretty up and this was a lower, quieter moment.

GL: Since we had been on tour with a string ensemble last year, the idea of bringing an extra person on stage wasn’t foreign anymore.

AL: [Fans] loved it. The great thing about playing it live was you don’t know what was going to happen. You hope you get through without a horrible trainwreck. It’s exciting to break away from the regimented, rehearsed stuff we normally do.

“Tom Sawyer” (1981)

GL: There was some doubt as to whether it would even go on the record at one point, because we struggled with it for a long time. [Engineer] Paul [Northfield] came up with this weird way of mic-ing [Al’s] amp that created that super interesting ambient sound.

AL: And then the song came to life.

GL: That’s really when the song took off. There’s always a track that just drives you effing crazy, and that was the one on [1981’s Moving Pictures]. I never thought it would end up being the most popular song we’ve ever written.

AL: It’s a quirky song. It was so hard to get it to feel right — but in the end, we clearly did.

“YYZ” (1981)

GL: Neil and I started jamming and he came up with this Morse code rhythm. I ended up writing the skeleton of the song on bass and drums. Then Al came in and added his parts and the thing blossomed.

AL: The Morse code came from a flight back to Toronto. I had a friend who picked us up in a Piper Aztec, a little six-seater plane. The Morse code notifier for Toronto was YYZ. We were listening to it and Geddy or Neil commented on the rhythm of it, what a cool rhythm that would be.

“Closer to the Heart” (1977)

GL: The lyrics had a great sentiment and seemed to beg a more thoughtful, less hyper approach.

AL: We both wrote it on acoustics — those earlier records, that’s what we used. We used our imaginations a lot.

GL: We were on the road all the time, so we would end up writing in a shitty hotel room or in the back of the car. We would play a show and sometimes we would just go back to the hotel once the headliner was on and we would just jam.

AL: A lot of [1975’s] Fly by Night was written in the backseat of the station wagon that we had.

GL: If you sit with an acoustic guitar and you strum hard, it’s got a heaviness to it that’s implied. When you plug into an amp, you f— around with that amp forever and it distracts you from what you’re actually trying to do, which is just write notes. So writing on acoustic simplifies and keeps you connected in the writing process.

“2112” (1976)

GL: We thought we were really smart. [Rush] couldn’t do that now, because [we’re] not armed with the same naiveté. That naiveté makes you a bit more audacious — and great art comes from audacity. When writing a book in science fiction there are no rules. You can make any s–t up you want. The same thing goes for us musically. You can use all kinds of sounds and it all can be rationalized by the story that you’re telling that’s set in a different time-space continuum.

AL: This was after Caress of Steel, which was not a very commercially successful record, so there was a real funk around us. Everybody was kind of down. There was a lot of pressure on us to make a different kind of rock record.

GL: When we got signed, people expected us to be the next Humble Pie or the next Bachman-Turner Overdrive or Bad Company. Those were the bands that were big right then. They thought we were just going to be another one of those. And then we started smoking a lot of hash oil and we went in a different direction. [pauses] Fooled ya!

“Anthem” (1975)