INTRODUCTION. 



THE earliest and fundamental conceptions of 

 men respecting the objects with which Astro- 

 nomy is concerned, are formed by familiar pro- 

 cesses of thought, without appearing to have in 

 them anything technical or scientific. Days, Years, 

 Months, the Sky, the Constellations, are notions 

 which the most uncultured and incurious minds 

 possess. Yet these are elements of the Science of 

 Astronomy. The reasons why, in this case alone, 

 of all the provinces of human knowledge, men 

 were able, at an early and unenlightened period, 

 to construct a science out of the obvious facts of 

 observation, with the help of the common furniture 

 of their minds, will be more apparent in the course 

 of the philosophy of science ; but I may here barely 

 mention two of these reasons. They are, first, that 

 the familiar act of thought, exercised for the com- 

 mon purposes of life, by which we give to an 

 assemblage of our impressions such a unity as is 

 implied in the above notions and terms, a Month, 

 a Year, the Sky, and the like, is, in reality, an 

 inductive act, and shares the nature of the pro- 

 cesses by which all sciences are formed; and, in 

 the next place, that the ideas appropriate to the 

 induction in this case, are those which, even in 



