Arguably the most famous Rush song ever recorded, "Tom Sawyer" grew from a melody Lee had been using to set up his synthesizers at sound checks. The lyrics were co-written with Pye Dubois of Max Webster — the two bands had recently collaborated on Max Webster's "Battle Scar," which featured all seven musicians playing together at Phase One Studios. The song paints an abstract portrait of a defiant, free-thinking individual — a "modern day warrior" who answers to no authority.
It was the most difficult song on the album to get right. The band had periods of genuine doubt about whether it would work. It features a 4/4 backbeat with instrumental sections shifting into 7/8 time, and was the first Rush recording where Lee used his 1972 Fender Jazz Bass, which provided a punchier tone than his usual Rickenbacker. That bass became his primary studio instrument from Counterparts onward.
"Tom Sawyer" hit #1 on the U.S. Mainstream Rock chart and #44 on the Hot 100 — by far Rush's biggest single. It has become one of the most enduring songs in classic rock radio history, appearing in countless films, TV shows, and video games. It was performed at virtually every Rush concert from 1981 until the final R40 show in 2015.