Introduction: Beyond the world we know, by the authors.--The Odyssey, by Homer --Timaios, by Plato.--A journey to the moon, by C. de Bergerac.--The new accelerator, by H. G. Wells --The cats of Ulthar, by H. P. Lovecraft --A Martian odyssey, by S. G. Weinbaum.--Helen O'Loy, by L. del Rey.--The cold equations, by T. Godwin --A gun for dinosaur, by L. S. de Camp --Before Eden, by A. C. Clarke --The last question, by I. Asimov --Bibliography (p. [255]-256).