"Horizons" was written by Steve Hackett in 1972 and published on the Genesis "Foxtrot" album. The song was completed in the course of a year, and took musical inspiration from the Prelude of Suite No. 1 in G major, BWV 1007 for cello by Johann Sebastian Bach.
Horizons is one of the most beautiful songs ever written for classical guitar.
The sheet music can be found here: Horizons Sheet Music