When a retrofit of electric guitars transformed "Sounds of Silence" into Simon & Garfunkel's folk-rock entrée, the partners and their label hastily followed with a like-titled album mixing Paul Simon's acoustic folk songs with plugged-in bids for radio play. By contrast, this successor, released less than a year later, more coherently and convincingly reveals Simon's broadening horizons as a writer and the duo's nascent studio perfectionism. The title song remains a haunting signature piece, relying on acoustic guitar and harpsichord to carry its contrapuntal marriage of English ballad and antiwar plaint; such acoustic delicacy prevails throughout and has proven more durable than by-the-numbers wattage. The first great S&G album, the set includes "The 59th Street Bridge Song (Feelin' Groovy)," "Homeward Bound," "Dangling Conversation," and Art Garfunkel's luminous solo piece, "For Emily, Wherever I May Find Her." (The 2001 reissue adds a pair of unreleased demos to the original work.) --Sam Sutherland