686 THE POPULAR SCIENCE MONTHLY. 



and its victory in the struggle for life are connected with the brute 

 quantity of nervous excitation, independently of its quality. But this 

 view involves difficulties. How, for example, can we explain the fact 

 that some sounds and some odors are disagreeable in all their degrees ? 

 Again, fix your eyes upon a moderately lighted white surface ; you 

 will feel neither fatigue nor displeasure, but you will also experience 

 only a weak positive pleasure. Substitute a blue surface for the white 

 one. The blue ray, which was previously present in the white light 

 as one of its constituent elements, is now offered separately to your 

 eye, with the other rays eliminated, and your pleasure is increased. 

 The increase of pleasure can not be due to an increase of stimulus, for 

 the physical stimulus has been in fact diminished by the quantity of 

 light that has been eliminated. Your pleasure is no more due to a 

 diminution of fatigue, for there was nothing fatiguing about the 

 white. The agreeable nature of the blue is therefore associated with 

 the mode rather than with the degree of nervous action. An effect of 

 heredity and selection is also involved. Animated beings have for 

 many ages received the blue rays from the sky under which they 

 lived, and they have become hereditarily accustomed and adapted to 

 this luminous medium of clear days as well as to the green rays of the 

 fields and woods. It is, however, impossible to account for the details 

 of our sensory pleasures any more than for our aesthetic pleasures. All 

 that can be said is, generally, that the form or quality of the excita- 

 tion must be taken account of, as well as its quantity. 



If we examine the directions toward which the movements of the 

 organisms ultimately tend, we shall find that some tend to the pres- 

 ervation of the substance, others to its destruction ; some to life, 

 others to death. Pleasure is of victory in the struggle, of life, pain 

 of defeat, of death. All suffering is a partial death which comes upon 

 some organ or function. Darkness makes us sad because it extin- 

 guishes the sight ; discords, because the jangle of noises afflicts our 

 perception of sounds. Thus, everything that tends to obstruct and 

 annul a function of the senses produces annoyance and pain. So with 

 mental functions. We enjoy what we can understand clearly, for it 

 implies life and vigor of thought ; we are pained when we fail to 

 understand anything clearly, because that conveys an impression of 

 impotency of thought. The emotion of the sublime involves a min- 

 gling of sorrow and joy, because, in the immensity of that which excites 

 it, the possibility of perceiving the whole, of comprehending it all 

 in our eye or even in our imagination, is taken away from us ; but, by 

 a superior effort, we conceive the infinite, and annul the material ob- 

 stacle by the power of thought. We thus, at the same time, feel a 

 physical inferiority that depresses us, and a moral superiority that 

 raises us : we die in the world of sense, and are born again in the 

 world of mind. 



While Darwin discusses the struggle for existence, he does not 



