BOOK 11. xcTX. 214-216 



lands and indeed to the whole of nature in the same 

 processes of rising and setting, the course or other 

 operation of a star being manifest beneath the 

 earth in just the same way as when it is travelHng 

 past our eyes. 



Moreover, the lunar difference is manifold, and ra?! and 

 to begin with, its period is seven days : inasmuch as p^l-iojg^ 

 the tides, which are moderate from new moon to 

 half-moon, therefrom rise higher and at fuU moon 

 are at their maximum ; after that they relax, at the 

 seventh day being equal to what they were at first; 

 and they increase again when the moon divides on 

 the other side, at the union of the moon with the sun 

 being equal to what they were at fuU moon. When 

 the moon is northward and retiring further from 

 the earth the tides are gentler than when she has 

 swerved towards the south and exerts her force at 

 a nearer angle. At every eighth year the tides 

 are brought back at the hundredth circuit of the 

 moon to the beginnings of their motion and- to 

 corresponding stages of increase. They make all 

 these increases owing to the yearly influences of the 

 sun, swelling most at the two equinoxes and more at 

 the autumn than the spring one, but empty at mid- 

 winter and more so at midsummer. Nevertheless 

 this does not occur at the exact points of time I have 

 specified, but a few days after, just as it is not at 

 fuU or new moon but afterwards, and not immediately 

 when the world shows or hides the moon or slopes 

 it in the middle quarter, but about two equi- 

 noctial hours later, the effect of aU the occurrences 

 in the sky reaching the earth more slowly than the 

 sight of them, as is the case with Ughtning, thunder 

 and thunder-bolts. 



345 



