2 Experimental Philosophy. [Lecture 1. 



on which you stand, that revolves upon an axis, 

 and presents different parts of its surface to the 

 sun at certain hours of the day. Or, when you 

 :irc told tnis, do you not feel a wish to know the 

 proofs and the reasons of it; and why the sun 

 appears to n-iove, when in reality it is yourself, 

 or rather the earth on which you stand ? Have 

 patience, and you shall know all this; and it 

 will be as clearly proved to you as any common 

 fact, or as the result of any arithmetical operation. 



Again : You throw a stone, or shoot an arrow 

 upwards into the air ; Why does it not go for- 

 ward in the line or direction that you give it? 

 Why does it stop at a certain distance, and then 

 return back to you ? What force is it that presses 

 it down to the earth again, instead of its going 

 onwards ? On the contrary, Why does flame or 

 smoke always mount upwards, though no force is 

 used to send them in that direction ? And why 

 should not the flame of a candle drop towards the 

 floor, when you reverse it, or hold it downwards, 

 instead of turning up, and ascending into the air ? 



You look into a clear well of water, or on the 

 surface of a looking-glass, and you see your own 

 face and figure, as if it were painted there, and 

 even more correct than the best artist could draw 

 it. Why is this? You are certain there is no 

 such figure, either in the well or behind the 

 looking-glass. You are told this is done by 

 reflection. But what is reflection? It must be 

 some property in light, which occasions its being 



