Neil Diamond's half-century as a prolific singer, songwriter and recording artist (nearly four decades on Columbia Records) is one of the eternal verities of American popular music. He began taking pre-med studies at New York University, but was interrupted in 1962 by an offer to write songs for $50 a week at 1619 Broadway, the Brill Building. Like many writers there, including fellow Brooklynites Neil Sedaka and Carole King, Diamond was writing as much for himself as for others. Thus, "I'm a Believer" was grabbed by the Monkees, who turned it into the top song of 1966 (followed three months ...