Seriously, if there is an intelligence in Mars, it must have evolved along the same general lines as intelligence has developed on the Earth. Being an older planet, it must have outgrown many of the vagaries and illusions which still hamper man in his progress here. In the dim past, however, we can imagine some Martian astronomer with the enigma of our Earth before him, and the great vault of heaven with its thousands of riddles unanswered, consulting records and covering pages with mathematical formulæ to ascertain the precise spot upon which grew the bean stalk by which a Martian Jack ascended to encounter the giant. Indeed, the imagination can conjure up an infinite number of parallels. If Mars is an older sphere, we trust it has long outgrown the superstitions which still hamper man in his interpretation of the inexorable phenomena of Nature on this little planet. We may hope that they have finally reached that stage when a dictum similar to that of Huxley forms an engraved tablet in their temples of worship. These are his words: "Science is teaching the world that the ultimate court of appeal is observation and experiment, and not authority. She is teaching it to estimate the value of evidence; she is creating a firm and living faith in the existence of immutable moral and physical laws, perfect obedience to which is the highest possible aim of an intelligent being." XVI SCHIAPARELLI, LOWELL, PERROTIN, THOLLON _Every age has its problem, by solving which humanity is helped forward._ HEINRICH HEINE. In previous pages allusion has been made to the distinguished character of the astronomers who have contributed to a knowledge of the surface markings of Mars. Testimony from astronomical sources has been quoted as to their keen-sightedness in this work which, as Sir Robert Ball has said, "indicates one of the utmost refinements of astronomical observation." That the reader may better understand the eminence of some of those whose names will forever be associated with the investigation of the surface features of Mars the following brief records are given. [Illustration: GIOVANNI VIRGINIO SCHIAPARELLI]