BOOK II. xxr. 86-xxn. 89 



half the circle is subtracted by the interposition of 

 the earth at the centre, the measure of the sun's 

 altitude comprises about ^th of this conjecturally 

 estimated immense space of the solar circle round 

 the earth, and the moon's altitude yVth, since the 

 moon runs in a circuit that is much shorter than the 

 sun's ; so that it comes between the sun and the earth. 

 It is marvellous to what length the depravity of man's 

 intellect will go when lured on by some trifling 

 success, in the way in which reason furnishes impu- 

 dence with its opportunity in the case of the calcula- 

 tions above stated. And when they have dared to 

 guess the distances of the sun from the earth they 

 apply the same figures to the sky, on the ground that 

 the sun is at its centre, with the consequence that they 

 have at their finger's ends the dimensions of the 

 world also. For they argue that the circumference of 

 a circle is ^-- times its diameter, as though the measure 

 of the heavens were merely regulated from a plumb- 

 line ! The Egyptian calculation published by 

 Petosiris and Nechepsos infers that one degree of the 

 kmar circle measures (as has been said) just over 

 4g- miles at the least, one degree of the widest 

 circle, Saturn's, twice that size, and one of the sun's 

 circle, which we stated to be in the middle, the mean 

 between the other two. This computation is a most 

 shameful business, since the addition of the distance 

 of the zodiac itself to the circle of Saturn produces a 

 multiple that is even beyond reckoning. 



XXII. A few facts about the world remain. Conuts. 

 There are also stars that suddenly come to birth in ''"" 

 the heaven itself ; of these there are several kinds. 

 The Greeks call them ' comets,' in our language 

 ' long-haired stars,' because they have a blood-red 



231 



