The most indelible movie themes embrace more than mere cinematic concerns; they come to evoke entire eras, genres and virtual states of mind. Decades later the menacing locomotive rhythms of John Williams' Jaws theme still manage to do all three in but a few brief bars. As astute film buffs know, Steven Spielberg's career-making blockbuster relied on considerably more than his directorial skills and a trouble-plagued mechanical shark. Verna Field's shrewd, seamless editing and Williams' brooding orchestral score create a tension-wracked masterpiece of terror, one where the composer's brass-savvy writing evokes New England beachfront tranquility one moment, and gut-wrenching aquatic carnage the next. Like Bernard Herrmann's greatest scores, Williams relies more on mood-setting motifs than catchy melodies here, yet the unsettling results scored him the first Oscar of what has long since become one Hollywood's most fabled musical careers.