Book 4 of Lucan’s epic contrasts Europe with Africa.  At the battle of Lerida (Spain), a violent storm causes the local rivers to flood the plain between the two hills where the opposing armies are camped. Asso’s commentary traces Lucan’s reminiscences of early Greek tales of creation, when Chaos held the elements in indistinct confusion.  This primordial broth sets the tone for the whole book.  After the battle, the scene switches to the Adriatic shore of Illyricum (Albania), and finally to Africa, where the proto-mythical water of the beginning of the book cedes to the dryness of the desert.  The narrative unfolds against the background of the War of the Elements. The Spanish deluge is replaced by the desiccated desolation of Africa. The commentary contrasts the representations of Rome with Africa and explores the significance of Africa as a space contaminated by evil, but which remains an integral part of Rome. Along with Lucan’s other geographic and natural-scientific discussions, Africa’s position as a part of the Roman world is painstakingly supported by astronomic and geographic erudition in Lucan’s blending of scientific and mythological discourse.  The poet is a visionary who supports his truth claims by means of scientific discourse.