112 THE GREEK ASTRONOMY. 



CHAPTER I. 



EARLIEST STAGES OF ASTRONOMY. 



Sect. 1. Formation of the Notion of a Year. 



THE notion of a Day is early and obviously impressed upon man in 

 almost any condition in which we can imagine him. The recur- 

 rence of light and darkness, of comparative warmth and cold, of noise 

 and silence, of the activity and repose of animals ; the rising, mount- 

 ing, descending, and setting of the sun ; the varying colors of the 

 clouds, generally, notwithstanding their variety, marked by a daily 

 progression of appearances ; the calls of the desire of food and of 

 sleep in man himself, either exactly adjusted to the period of this 

 change, or at least readily capable of being accommodated to it ; the 

 recurrence of these circumstances at intervals, equal, so far as our ob- 

 vious judgment of the passage of time can decide ; and these intervals 

 so short that the repetition is noticed with no effort of attention or 

 memory ; this assemblage of suggestions makes the notion of a Day 

 necessarily occur to man, if we suppose him to have the conception of 

 Time, and of Recurrence. He naturally marks by a term such a por- 

 tion of time, and such a cycle of recurrence ; he calls each portion of 

 time, in which this series of appearances and occurrences come round, 

 a Day ; and such a group of particulars are considered as appearing 

 or happening in the same day. 



A Year is a notion formed in the same manner ; implying in the 

 same way the notion of recurring facts ; and also the faculty of arrang- 

 ing facts in time, and of appreciating their recurrence. But the notion 

 of a Year, though undoubtedly very obvious, is, on many accounts, 

 less so than that of a Day. The repetition of similar circumstances, at 

 equal intervals, is less manifest in this case, and the intervals being 

 much longer, some exertion of memory becomes requisite in order that 

 the recurrence may be perceived. A child might easily be persuaded 

 that successive years were of unequal length ; or, if the summer were 

 cold, and the spring and autumn warm, might be made to believe, if 

 all who spoke in its hearing agreed to support the delusion, that one 

 year was two. It would be impossible to practise such a deception with 

 regard to the day, without the use of some artifice beyond mere words 



