LESSONS OF EVOLUTION 623 



cheerful man, who cultivates the habit of happiness, finding 

 good reasons for rejoicing in the sunshine and stars, in 

 flowers and birds, in works of art and the faces of his friends 

 will have his ' joy-reward ' or euphoria added unto him 

 unless he is fool enough to pursue it. Our point is, that, 

 open to at least a large number of our fellow-creatures, there 

 are sights and sounds that make for joy and that increas- 

 ingly, as some of the Psalmists were well aware, and that 

 one of the obvious lessons of evolution and of common 

 sense is that wo should use these well-springs freely. 



What is true in regard to digestion applies also to other 

 functions. Wordsworth knew this when he spoke of his 

 heart responding to the sight of the rainbow and the recollec- 

 tion of the daffodils by the lakeside. He may not have 

 known much about the complex pathways of the pneumo- 

 gastric, but he was sure about the influence of joy on the cir- 

 culation. Professor Dearborn has worked at the factors alter- 

 ing blood-pressure and he makes the notable statement that 

 in the "general stimulation of the essential circulation in 

 all constructive parts of the body, such as the brain, the 

 muscles, and the digestive organs, joy exerts one of its 

 most conspicuous benefits, and one that no one can doubt 

 or ignore ". 



There are facts which point to the conclusion that a glad- 

 some mind may also increase the integrative function of the 

 nervous system. It is an indubitable fact that a joy say 

 of maternity, or discovery, or artistic creation may become 

 an exhilaration and enthusiasm of thought and will; but 

 the same is true of bodily welfare. Good tidings will 

 invigorate the flagging energies of a band of explorers; an 

 unexpected visit will change a wearied homesick child, as 

 if by magic, into a dancing gladsome elf; a religious joy 



