3. The third circle is called ἰσημερινὸς, which is equivalent to _equinoctialis_ in Latin, for the reason that when the sun comes to this circle it makes equal day and night (for ἰσημερινὸς means in Latin day equal to the night) and by this circle the sphere is seen to be equally divided. The fourth circle is called Antarctic,[271] for the reason that it is opposite to the circle which we call Arctic. [271] This order is repeated in 13, 6. 4. The fifth circle is called the winter tropic (χειμερινὸς τροπικός), which in the Latin is _hiemalis_ or _brumalis_, because when the sun comes to this circle it makes winter for those who are in the north and summer for those who dwell in the parts of the south. Chapter 47. On the size of the sun. 1. The size of the sun is greater than that of the earth and so from the moment when it rises it appears equally to east and west at the same time.[272] And as to its appearing to us about a cubit in width, it is necessary to reflect how far the sun is from the earth, which distance causes it to seem small to us. [272] This passage indicates Isidore’s belief in a flat earth. See pp. 51–54. Chapter 48. On the size of the moon. 1. The size of the moon also is said to be less than that of the sun. For since the sun is higher than the moon and still appears to us larger than the moon, if it should approach near to us it would be plainly seen to be much larger than the moon. Just as the sun is larger than the earth, so the earth is in some degree larger than the moon. Chapter 49. On the nature of the sun. 1. The sun, being made of fire, heats to a whiter glow because of the excessive speed of its circular motion. And its fire, philosophers declare, is fed with water, and it receives the virtue of light and heat from an element opposed to it. Whence we see that it is often wet and dewy. Chapter 50. On the motion of the sun. 1. They say that the sun has a motion of its own and does not turn with the universe. For if it remained fixed in the heavens all days and nights would be equal, but since we see that it will set to-morrow in a different place from where it set yesterday, it is plain that it has a motion of its own and does not move with the universe. For it accomplishes its yearly orbits by varying courses, on account of the changes of the seasons. 2. For going further to the south it makes winter, in order that the land may be enriched by winter rains and frosts. Approaching the north it restores the summer, in order that fruits may mature, and what is green in the damp weather may ripen in the heat. Chapter 51. What the sun does. 1. The rising sun brings the day, the setting sun the night; for day is the sun above the earth, night is the sun beneath the earth. From the sun come the hours; from the sun, when it rises, the day; from the sun, too, when it sets, the night; from the sun the months and years are numbered; from the sun come the changes of the seasons.