"Symptom of the Universe" was composed largely by guitarist Tony Iommi with lyrics by Geezer Butler and pointed the way toward thrash metal in the 80's. The song's closing passage, very disparate from the rest of the song, evolved from an in-studio jam. It was created very spontaneously in a single day and the decision was made to incorporate it into the song.
The authorship is really a Frankenstein job. I had a hand in almost every detail but is was truly a team effort. Thanks to everyone listed above.