246 TROPICAL NATURE, AND OTHER ESSAYS 



cannot denote colours only, as we perceive and differentiate 

 them ; but seem more applicable to different intensities 

 of light and shade. Thus, to give one example, the 

 word porphureos is applied to clothing, to the rainbow, 

 to blood, to a cloud, to the sea, and to death ; and no 

 one meaning will suit all these applications except com- 

 parative darkness. In other cases the same thing has 

 many different epithets applied to it according to its 

 different aspects or conditions ; and as the colours of 

 objects are generally indicated in ancient writings by 

 comparative rather than by abstract terms, as wine- 

 colour, fire-colour, bronze-colour, &c. it becomes still 

 more difficult to determine in any particular case what 

 colour was really meant. Mr. Gladstone's general con- 

 clusion is, that the archaic man had a positive perception 

 only of degrees of light and darkness, and that in 

 Homer's time he had advanced to the imperfect dis- 

 crimination of red and yellow, but no further ; the 

 green of grass and foliage or the blue of the sky being 

 never once referred to. 



These curious facts cannot, however, be held to 

 prove so recent an origin for colour-sensations as 

 they would at first sight appear to do, because we 

 have seen that both flowers and fruits have become 

 diversely coloured in adaptation to the visual powers of 

 insects, birds, and mammals. Red, being a very common 

 colour of ripe fruits which attract birds to devour them 

 and thus distribute their seeds, we may be sure that the 

 contrast of red and green is to them very well marked. 

 It is indeed just possible that birds may have a more 

 advanced development of the colour- sense than mammals, 

 because the teeth of the latter commonly grind up and 



