In the final scene, with the massacre and Zed/Consuela growing old
together, the music is from the second movement of Beethoven's 7th
symphony. I think it worked really well. I have heard that a movie's
music can be described as a separate "character" that can drive the
movie's actions, and using that particular bit of music was really
effective in conveying the emotion of the scene. If anybody else has
anything to say about the music in Zardoz, feel free to post a reply here.