Carly Simon shares 'Vain' secret with Taylor Swift
Duet at concert re-ignites four-decade old question
POSTED: 08:00 PM EDT Jul 30, 2013
UPDATED: 10:25 AM EDT Jul 31, 2013
Music legend Carly Simon teamed up with Taylor Swift and they swiftly re-ignited that four-decade old question... who's so vain?