You must have seen a learned astrologer placing before him a tablet covered with sand. He draws on it figures and pictures and shows on it the position of the stars and the planets, the heaven as well as the earth. Sometimes he presages from the position of the heavenly bodies and sometimes from the position of the earth. He traces also on this tablet the constellations and the signs of the Zodiac, the rising and the setting of the stars, deduces from them good and bad omens and draws the house of birth or of death. When in consonance with these signs he has prepared the horoscope showing good or ill luck, he sets aside the tablet and scatters the sand. No trace remains of all those drawings and pictures.
The surface of the earth is similar to this tablet. If you do not possess the strength to resist the temptations of this world, go, turn away from it and sit in a corner. If you have not got the necessary vigour to endure the hardships of this road, were you all stone, you would not weigh one straw.