In the days of Kepler we know that astrology was more thought of than astronomy, for though on behalf of the world he worked at the latter, for his own daily bread he was in the employ of the former, making almanacks and drawing horoscopes that he might live. CHAPTER XIV. TIME AND THE CALENDAR. The opinions of thinkers on the nature of time have been very varied. Some have considered time as an absolute reality, which is exactly measured by hours, days, and years, and is as known and real as any other object whose existence is known to us. Others maintain that time is only a matter of sensation, or that it is an illusion, or a hallucination of a lively brain. The definitions given of it by different great writers is as various. Thus Kant calls it "one of the forms of sensibility." Schelling declares it is "pure activity with the negation of all being." Leibnitz defines it "the order of successions" as he defined space to be the order of co-existences. Newton and Clarke make space and time two attributes of the Deity. A study of the astronomical phenomena of the universe, and a consideration of their teaching, give us authority for saying, that neither space nor time are realities, but that the only things absolute are eternity and infinity. In fact, we give the name of time to the succession of the terrestrial events measured by the motion of the earth. If the earth were not to move, we should have no means of measuring, and consequently no idea of time as we have it now. So long as it was believed that the earth was at rest, and that the sun and all the stars turned round us, this apparent motion was then, as the real motion of the earth is now, the method of generating time. In fact, the Fathers said that at the end of the world the diurnal motion would cease, and there would be no more time. But let us examine the fact a little further. Suppose for an instant that the earth was, as it was formerly believed to be, an immense flat surface, which was illuminated by a sun which remained always immovable at the zenith, or by an invariable diffused light--such an earth being supposed to be alone by itself in the universe and immovable. Now if there were a man created on that earth, would there be such a thing as "time" for him? The light which illumines him is immovable. No moving shadow, no gnomon, no sun-dial would be possible. No day nor night, no morning nor evening, no year. Nothing that could be divided into days, hours, minutes, and seconds. In such a case one would have to fall back upon some other terminating events, which would indicate a lapse of time; such for instance as the life of a man. This, however, would be no universal measure, for on one planet the life might be a thousand years, and on another only a hundred.