298 NATURAL THEOLOGY. 



ties of the garden and of the landscape would 

 have been lost to us. How is the beauty of the 

 latter enhanced by the almost infinite variety of 

 colour, yet still vv^ithin that range vv^hich is agreea- 

 ble Euid soothing to the eye, as well as consonant 

 to our feelings ! The human countenance, too, 

 although capable of exciting our warmest sympa- 

 thies by form and motion alone, has that beauty 

 perfected by colour, varying under the influence 

 of emotion. 



It remains, in order that we may apply these 

 facts to the explanation of the structure of the eye, 

 to show how the rays proceeding from a body 

 and falling upon a convex glass suffer refraction. 

 The ray that strikes upon the centre being per- 

 pendicular to the glass, passes on undeviatingly. 

 But each ray as it strikes a point removed from 

 the centre, must impinge with more obliquity, in 

 consequence of the curved surface ; and as the 

 refraction of all the rays will be in proportion to 

 the obliquity of their incidence, they will converge 

 towards the central direct ray. Thus a, as it 

 passes through the glass, suffers refraction towards 



