Human emotions are the subject of The Passions, a series of 20 video works made by the contemporary artist Bill Viola (b. 1951). Since the mid-1970s, Viola's video installations have dealt with themes of perception, memory and self-knowledge. In these new works he has grappled with one of the oldest problems in art: how to convey the power and complexity of emotion by depicting the facial expressions and body language of models or, in Viola's case, of performers.