the general facts known about the planet, before taking up the observations which make the subject matter of this book. The first of these general facts is the path the planet describes about the Sun. Who first found out that the ruddy star we call Mars was not like the rest of the company about him we do not know; possibly some, to fame unknown, Chaldean shepherd alone with the night upon the great Chaldean plains. With the stars for sole companions while his sheep slept, he must, as he watched them night after night, have early recognized that they always kept the same configuration. They rose and set, but they all rose and set together. But one night he thought he noticed that one of them had changed its place with reference to the rest. A few nights later he became sure of it. One of the immovable had patently moved. That memorable though unremembered night marked the birth of our acquaintance with the rest of the universe.
Whether the midnight pioneer was Chaldean or Assyrian or of some other race, certain it is that to the Egyptians we owe the first systematic study of the motions of this and of four other roving stars, and to the Greeks whom they taught, the name by which we know them, that of planets, meaning merely wanderers. Since then, as we know, many others of like habit have been added to the list.