66 Dr. Herschel on the Nature and Construction 
undergoing the same regular changes of illuminations as the 
moon does to the earth. The sun, the planets, and the starry 
constellations of the heavens, will rise and set there as they do 
here ; and heavy bodies will fall on the moon as they do on 
the earth. There seems only to be wanting, in order to com- 
plete the analogy, that it should be inhabited like the earth. 
To this it may be objected, that we perceive no large seas in 
the moon ; that its atmosphere (the existence of which has 
even been doubted by many) is extremely rare, and unfit for 
the purposes of animal life ; that its climates, its seasons, and 
the length of its days, totally differ from ours ; that without 
dense clouds (which the moon has not), there can be no rain ; 
perhaps no rivers, no lakes. In short, that, notwithstanding 
the similarity which has been pointed out, there seems to be a 
decided difference in the two planets we have compared. 
My answer to this will be, that that very difference which is 
now objected, will rather strengthen the force of my argument 
than lessen its value : we find, even upon our globe, that there 
is the most striking difference in the situation of the creatures 
that live upon it. While man walks upon the ground, the birds 
fly in the air, and fishes swim in water ; we can certainly not 
object to the conveniences afforded by the moon, if those that 
are to inhabit its regions are fitted to their conditions as well 
as we on this globe are to ours. An absolute, or total same- 
ness, seems rather to denote imperfections, such as nature 
never exposes to our view ; and, on this account, I believe the 
analogies that have been mentioned fully sufficient to estab- 
lish the high probability of the moon's being inhabited like the 
earth. 
To proceed, we will now suppose an inhabitant of the moon, 
