The desire to know, for the pure delight of knowing, had perhaps hardly begun to dawn upon the mind of man. What people did want to know was what might be going to happen to themselves; whether _they_ would be happy or unhappy; and the stars were chiefly of interest as appearing to tell beforehand of troubles or joys to come. The wisest of men in those times knew less of the outspread heavens than many a child now knows in our public schools. Earth and sky were one vast bewildering puzzle. They had to discover everything for themselves--how the sun rose each morning and set each evening; how the seasons changed in steady sequence through the year; how the moon and stars journeyed in the night; how the ocean-tides went and came; how numberless every-day phenomena took place. In olden days the daily rising and setting of the sun was a mystery, accounted for by divers theories, none of which were right; and the march of stars across the midnight sky was a complete puzzle; and an eclipse of sun or moon was a fearful perplexity; and the tides of ocean were a great bewilderment. These things are mysteries still to barbarous nations; but they perplex us no longer, because we have found out the mode in which such movements, or appearances of movement, are brought about through the action of quite natural causes. As a first step, in earliest times, the journey of the sun by day, the journeys of moon and stars by night, across the sky, could hardly fail to arrest attention. Very early, too, the stars were grouped into constellations, definite figures and names being attached to each. Many of the constellations are now known to us by names which belong to the earliest historic ages. The stars were known as “fixed,” because they continued unchangeably in their relative positions--that is, in the position held by each star with respect to its neighbor stars--although the whole array of them moved nightly in company; constellations rising and setting at night, as the sun rose and set in the day. Ages may well have passed before the planets were recognized as distinct from the fixed stars; ages more before any definite plan was noted in their wanderings. In the course of time men’s attention was directed to these matters; and one fact after another, of daily or monthly or yearly occurrence, was observed, and commented upon, and became familiar to the minds of people. Very slowly the first beginnings of systematized knowledge took shape and grew, one discovery being made after another, one explanation being offered after another, one theory being started after another.