“Sentimentality is the failure of feeling,” Wallace Stevens once said. Maybe so, but Tom Waits’ uncanny ability to legitimize nostalgia as an art form unto itself is a rare gift ; if poets were presidents, Stevens might consider Waits worthy of a pardon. On his second album, Tom Waits begins to convincingly adopt many of the personas he would return to, in various forms, throughout his career : the twisted Vaudeville crooner ; the maudlin, luckless barfly ; the “pool-shootin’ shimmy-scheister.” Even the cover art, a painting depicting Waits as some combination of reluctant lothario and boxcar stowaway, is pitch-perfect. Waits relies on showbiz affectations the way a priest might don a ceremonial robe : by getting into character, he is better able to transcend his reality, perceived as earthly or mundane. In doing so he retains the tunefulness of his mediocre debut while taking a few more stylistic chances, with sterling results: the title track uses metropolitan field recordings and a stomach-gurgle-sounding fretless bass as a bedrock for an episodic narrative equal parts Joni and Zimmy; the gorgeous “San Diego Serenade” is poignant and astute ; and “Semi Suite” is a slow bebop ballad complete with muted trumpet and the sort of vaguely lascivious torch singing you’d commonly associate with Lady Day. But the most interesting aspect of The Heart Of Saturday Night is its intersection of Waits the sophisticated balladeer and Waits the jive-talkin,’ snake oil-sellin,’ tall tale-tellin’ barroom bullshitter, the sound of Jekyll confronting Hyde in the pages of some lowlife Charles Willeford novel. Rarely would these two disparate personalities sit as cozily or as compatibly.