In order to calculate time, they next devised the zodiac, a sort of belt encircling the heavens and showing the course of the sun, and the location of twelve constellations, or groups of stars, through which he would be seen to pass if his light did not blot out theirs. They divided the region of these twelve constellations into the same number of equal parts; consequently, the sun passing from any given point around the heavens to the same point, occupied in so doing an amount of time that was arbitrarily divided into twelfths. But they also devised another twelve-part division of the year. They noticed that the moon went through her phases, from full moon to full moon in about thirty days. So one moon, or one month, corresponded with the passage of the sun through one "sign" of the zodiac. Our own word "month" might have been written "moonth," since that is its meaning. That gave them a year of twelve months, each month having thirty days, or three hundred and sixty days in all. Then from the seven heavenly bodies which they had identified with seven great gods, they got the idea of a week of seven days, one day for the special worship of each god and named for him. In like manner, they divided the day and the night each into twelve hours; and the hour into sixty minutes and these again into sixty seconds. The choice of "sixty" was not a chance shot or accident; it was carefully selected for practical reasons since these old astronomers were wise and level-headed men. No lower number can be divided by so many other numbers as can sixty. Just look at your watch for a moment and notice how simply and naturally the minutes, divided into fives, fit into place between the figures for the hours, and, because sixty divides evenly by fifteen and thirty, we have quarter-hours and half-hours. Therefore, we should realize, with a bit of gratitude, that we owe these divisions of time, of which we still make use, to the ancient magician-priests of Babylon and Chaldea, thousands and thousands of years ago. In doing all this, these early scientists developed at the same time an elaborate system of so-called "magic" by which they pretended to foretell future events and the destinies of men born on certain days. This was an important part of their priestcraft, and probably it was not the least profitable part. In fact, the priests called themselves _magi_, meaning "wise men" in their language, and our word "magic" is derived from "magi."