"Finding one particular thing at one particular time, then letting a world accumulate around it, in rough contingency, nothing quite fitting or not fitting." This is how Dave Hickey describes the work of artist and singer-songwriter Terry Allen, who creates works that proliferate into a constellation of genres as he revisits and revises his original inspirations. A painting may lead to a sculpture, which morphs into a song that takes on many voices and becomes a theatre piece or video installation. Yet, in Allen's endlessly evolving art, "nothing that you might actually see in the world is...