Spanish surrealist painter Remedios Varo created the metaphor shown here for Einstein's space-time Universe in 1963. The Phenomenon of Weightlessness, as it is called, is one of over 300 illustrations in Exploring the Invisible: Art, Science and the Spiritual (Princeton University Press, $49.95) by the art historian Lynn Gamwell. The book, which is scholarly but highly readable, follows the history of the way that scientific thought and discovery has influenced art, particularly since the latter half of the nineteenth century.