This is one of the greatest duets of all time. You forget that this is a cover of a Marvin Gaye and Tammi Terrell song because Luther really does "Lutherize" it. This is just an example of a timeless song because someone could remake it today and it would still be relevant. The song would still have it's meaning.
By the way it was written by Motown superstar, Marvin Gaye.