LESSONS OF EVOLUTION ()2;3 



cheerful man, who cultivates the habit of happiness, tiiiding 

 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 adik'd 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 connnon 

 sense — is that we 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 pneunio- 

 ffastric, 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 



