Rush consumed lots of prog rock before conquering the genre in the '70s. Genesis' intricate sci-fi epic “Watcher of the Skies” taught them about acrobatic time changes and multi-part composition, and Yes' drifting ballad “Time and a Word” exposed them to classical harmonies and melodies. But Rush are also riff-loving hard rockers who picked apart the thunderous jamming in Cream's blues-rock beast “Crossroads.”