Wilson was rather at odds with recording process rationality at the time due to his LSD use exacerbating his inner childhood demons and a nervous breakdown he once suffered on tour.Idealisims and visions came in and out of his head faster than he could really properly process and present them in an audience accessible manner.As result of his psychological struggles,he became highly unduly obsessed with doing "Vibrations" in extreme exacting fashion,causing the Beach Boys to work on the track for about six months,which is why it wound up on "Smiley Smile" instead of it's intended placement on "Pet Sounds".The follow up to "Pet Sounds" was originally titled simply "Smile" and Wilson ceased production on another of his "symphonies to God" the moment he heard "Sgt. Pepper" as he was out to create the greatest rock album ever made and felt the Beatles had pretty much put out a record of insurmountable greatness.He did finish and release the project in 2004,but I always have the gnawing feeling the project may have been better undertaken had it been finalized back in '66 or '67 while all of his ideas for the records were still much fresher in his mind and also because by the time he finished things up in the 2000's,his voice had lost a certain quality due to age.While Wilson didn't get involved with acid to the extent of Syd Barrett,he did,however,indulge in the psychotropic substance enough to inflict serious damage on his cohesive thought process and this in turn prevented the release of what might have been one of the best albums ever made.He just couldn't keep things together enough mentally.I've heard there are some tapes from the original "Smile" sessions still in existence and though incomplete,might still be quite fascinating to hear.............