After accidentally realizing that he was a musical genius, Brian Wilson stepped up his efforts by the mid 60s.  Looking for a more serious direction, he began collaborating with lyricist Tony Asher, who helped interpret Brian’s musical ideas into focused lyrical concepts.  The increased level of lyrical and musical sophistication also stretched the limits of what was acceptable in pop music in 1966.  There weren’t practically any pop songs from that era with “God” in the title, and putting that word in the title was the source of great anguish to Brian as he was convinced it would ruin the chances of the song being a hit.  It was a hit in Europe, but only a minor success in America.  The song was an even bigger hit with Wilson’s contemporaries.  Paul McCartney has consistently rated “God Only Knows” as his favorite song ever, and it clearly influenced him to keep ramping up his sophisticated brand of mid 60s pop.  The song’s success with McCartney might have actually ended up being a negative for Brian’s psyche.  McCartney was already busy with Revolver, a masterpiece that would equal, if not surpass Pet Sounds, and nary a year later Paul and the Fabs came out with Sgt. Pepper.  There was no way Brian could compete with that level of production, and the pressure to match the Beatles led to his famous nervous breakdown.  It’s really too bad because when Brian wasn’t losing his mind, he was one of the greatest songwriters in American history.  One last fun fact, its actually Carl Wilson singing the lead vocal on the track.  Brian gave his brother the vocal because he liked Carl’s natural delivery on the song.  Nice guy that Brian Wilson.