Natural Science

The album closer is a three-part suite — "Tide Pools," "Hyperspace," and "Permanent Waves" — that serves as a bridge between Rush's progressive past and their streamlined future. The opening section paints a vivid picture of life in a tide pool as a metaphor for the natural world's complexity and fragility. It was initially conceived during rehearsals at Lakewoods Farm as, in Peart's words, "a giant hodge-podge of instrumental mish-mash" titled "Uncle Tounouse."

The piece moves from delicate acoustic passages through explosive progressive sections to a powerful, anthemic conclusion. At nine minutes, it proved the band could still craft extended compositions that felt organic rather than bloated — every section earns its place.

"Natural Science" is widely considered one of Rush's greatest achievements, often ranked among their top songs by fans. It was revived for the Time Machine tour in 2010-11 to rapturous responses, and its environmental themes have only grown more relevant with time. It serves as the perfect closing statement for an album that reinvented Rush without abandoning what made them special.