CHAPTER V 



THE BIOLOGY OF HEALTH 



§ 1. The Meaning of Health. — §2. The Body as Engine — and 

 More. — § 3. The Nervous System. — § 4. The Regulative 

 System. — § 5. What is Disease ? 



§ 1 The Meaning of Health 



WE need not delay over definitions of health, for 

 every one knows in a general way what the 

 priceless gift means. It is much more than the absence 

 of disease, it implies a positive quality of versatile 

 vigour ; and that depends on the harmonious working 

 of the chief parts of the body. It need not mean great 

 strength, a powerful dray-horse is often far from healthy, 

 but it always implies a pleasurable efficiency. It is 

 the condition which a man describes when he says he is 

 feeling " very fit," when he is able for vigorous and 

 enduring self-expression. He feels " a man for a' that,'' 

 not, as Samuel Butler said, a mere appanage of his wife 

 or some other near relative. 



But we have to widen this idea of internal fitness by 

 recognising that the ideal of health includes fitness to 

 the external conditions of life in so far as these are 

 of a kind that make for the conservation and enrich- 



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