Really, everything this folk duo released from 1964-1968 is essential. That includes the rather green bluegrass of Wednesday Morning, 3 AM, the stark disillusionment that colored Sounds of Silence, the warmth of Bridge Over Troubled Water and everything in between.
Only Stevie Wonder, Creedence Clearwater Revival, The Ramones and a few other American artists had such a consistent, productive run.
In some ways, "The Boxer" combines all the best elements into one melodic poem: touching, observational poetry; acoustic softness; and sparse electric overlays that showed the pair's studio finesse. It remains a highlight of the nation's songwriting canon, evidence of what could be done when traditional folk met rock and pop head on.