‹‹‹ Vitr. 9.1.5 | Table of Contents | Vitr. 9.1.7 ›››
6The sun, in the course of a month, passes through the space of one sign which is a twelfth part of the heavens; hence in twelve months going through the twelve signs, when he has returned to that sign from which he set out, the period of a year is completed: but that circle which the moon passes through thirteen times in twelve months, the sun passes through only once in the same time. The planets Mercury and Venus nearest the rays of the sun, move round the sun as a centre, and appear sometimes retrograde and sometimes progressive, seeming occasionally, from the nature of their circuit, stationary in the signs.
6The sun takes a full month to move across the space of one sign, that is, one twelfth of the firmament. Consequently, in twelve months he traverses the spaces of the twelve signs, and, on returning to the sign from which he began, completes the period of a full year. Hence, the circuit made by the moon thirteen times in twelve months, is measured by the sun only once in the same number of months. But Mercury and Venus, their paths wreathing around the sun’s rays as their centre, retrograde and delay their movements, and so, from the nature of that circuit, sometimes wait at stopping-places within the spaces of the signs.