48 pltnt's KATTJEAL HISTOET. [Book II. 
extremities of their orbits on either side, the stars are then 
supposed to haye proceeded to their greatest distance ; when 
they hafve been a certain number of degrees within their 
orbits, they are then supposed to return more rapidly, since 
the extreme point in each is the same. And on this account 
it is that the direction of their motion appears to be changed. 
Por the superior planets are carried along the most quickly 
in their evening setting, while these move the most slowly ; 
the former are at their greatest distance from the earth 
when they move the most slowly, the latter when they move 
the most quickly. The former are accelerated when nearest 
to the earth, the latter when at the extremity of the circle ; 
in the former the rapidity of the motion begins to 
diminish at their morning risings, in the latter it begins to 
increase ; the former are retrograde from their morning to 
their evening station, while Venus is retrograde from the 
evening to the morning station. She begins to increase her 
latitude from her morning rising, her altitude follows the 
sun from her morning station, her motion being the quickest 
and her altitude the greatest in her morning setting. Her 
latitude decreases and her altitude diminishes from her 
evening rising, she becomes retrograde, and at the same 
time decreases in her altitude from her evening station. 
Again, the star Mercury, in the same way, mounts up in 
both directions^ from his morning rising, and having followed 
the sun through a space of 15 degrees, he becomes almost sta- 
tionary for four days. Presently he diminishes his altitude, 
and recedes from his evening setting to his morning rising. 
Mercury and the Moon are the only planets which descend 
for the same number of days that they ascend. Venus 
ascends for fifteen days and somewhat more ; Saturn and 
Jupiter descend in twice that number of days, and Mars in 
four times. So great is the variety of nature ! The reason 
of it is, however, evident ; for those planets which are forced 
up by the vapour of the sun likewise descend with difficulty. 
CHAP, 15. — GENEEAL LAWS^ OE THE PLAMTS. 
There are many other secrets of nature in these points, as 
1 "utroque modo;'* "latitudine et altitudine ; " Hardouin in Le- 
maire, ii. 279. ^ " CathoUca." 
