Johannes Kepler is remembered today chiefly for the 3 laws of planetary motion known after him. Rejecting the view of those who regarded astronomical hypotheses as mathematical fictions, Kepler sought to derive the true motions of the planets from physical causes. Yet he combined his search for physical causes with a vision of the world as a manifestation of divine harmony. This led him to consider the formal causes or archetypes underlying the world"s construction. Kepler"s favorite astronomical work, Harmony of the World (Harmonice mundi), was planned in 1599 as a sequel to the Mysterium cosmographicum, although it was not completed & published until 1619. In this vol., the translators have put the Harmony of the World into the kind of clear but earnest language which they suppose Kepler would have used if he had been writing today. Illus.