On the back cover of the three-CD box set Old Friends: Simon & Garfunkel, Paul Simon and Art Garfunkel are identified as "arguably the greatest pop duo of our time." Certainly, the string of hit singles that this pair of school buddies released between 1965 and 1970, all of which are featured here, support that assertion. Simon is a master of literate, intensely melodic songs, and the pairing of his evocative acoustic-guitar stylings and unaffected vocals with Garfunkel's silver-bell tenor is a match made in folk-pop heaven. From the plaintive grace of "The Boxer" to the surging "America" to the delicate, heartbreaking "Scarborough Fair/Canticle," these rank with the most moving and sonically gorgeous songs of their era. Also scattered among these 59 tracks are nine previously unreleased cuts, including a tender reading of the Christmas carol "Comfort and Joy" and a sparkling live performance of "Red Rubber Ball," a Simon-penned tune that was a hit for the Cyrkle in 1966. All told, this is an indispensable collection for fans of the duo -- and of truly timeless pop music.