THEORY OF THE FIRMAMENT. 13 



of astronomy may not prejudice the truth of a thing, and 

 that the decisions of philosophy may be such as may easily 

 be explained with regard to the phenomena of astronomy. 

 And so much for hypotheses. 



Now as to astronomical observations, which are assidu 

 ously accumulated, and continually are pouring down like 

 water from the sky, I have a great wish to admonish men 

 on that head ; lest, haply, that be true of them, which 

 is so elegantly fabled of the fly in jEsop, that sitting 

 on the harness of a chariot, contending for victory at the 

 Olympic games, cried out, &quot; see what dust / excite !&quot; Just 

 so, any petty observation, vacillating, at one time, in the 

 instrument, at this, in the eye, and at that, in a calculation, 

 and which possibly may be a reality, on account of some 

 true change in the heavens, calls into existence new firma 

 ments, new spheres, and new circles. And we do not make 

 these remarks in order that any relaxation in the taking of 

 observations or the study of history should take place, both 

 which we are of opinion should by all means be stimulated 

 and intently prosecuted; but only that, in rejecting or 

 changing hypotheses, the highest prudence and a mature 

 gravity of judgment be displayed. 



Wherefore, having now laid open the road as to the 

 motions themselves, we will say a few words also as to 

 their nature. We have already said, then, that there are 

 four kinds of motions of the higher order in the heavens : 

 an ascending and descending motion through the whole 

 expanse of the heavens ; a motion, to the breadth of the 

 Zodiac, stretching out towards south and north : a mo 

 tion in the course of the Zodiac, quick, slow, progressive, 

 retrograde, stable ; and the motion of elongation from the 

 sun. And let not any one object, that that second motion 

 of the breadth of the Zodiac or of the signs* thereof may 

 be referred to that great cosmical motion, since there is 

 an inclination by turns towards the south and the north ; 

 which as well as the curves themselves from one tropic 

 to the other are alike, except that the latter motion is 

 merely curvilinear, but the former hath also many turn 

 ings, and lies inmost at much less distances.f For neither 

 hath this point escaped our consideration. But assuredly 

 the constant and perpetual motion of the sun in the ecliptic, 

 considered apart from all latitude and exclusively of the 



* See note on &quot; dracones,&quot; page 10. 



t &quot; Te sinuoso in pectore fixi.&quot; Pers. 5, 27. 



