The sages said: When the sun is setting, the solar lustre becomes a circular mass without heat and enters the fire at night through his rays. Hence the light of fire is seen even from a distance at night. The heat is transmitted to the sun from fire, when the sun rises. Only partially does the terrestrial fire enter the sun. Hence the fire continues to blaze. Thus the fire element in both terrestrial and solar fires contains heat and light. They penetrate mutually and develop each other. In the northern and southern hemispheres of the earth, the fire and the sun thus develop each other. The sun rises up from the waters and re-enters them. Therefore, due to this exit (from and into waters) by day and by night, the waters become copper-coloured. Again when the sun sets, the day (i.e. daylight) enters the waters. Hence at night, the waters are seen shining white.