8 FATHERS OF BIOLOGY 



considered that while heat and cold, moisture and dry- 

 ness, succeeded one another throughout the year, the 

 human body underwent certain analogous changes which 

 influenced the diseases of the period. With regard to 

 the second class of causes producing diseases, he attri- 

 buted many disorders to a vicious system of diet, for 

 excessive and defective diet he considered to be equally 

 injurious. 



In his medical doctriries Hippocrates starts with the 

 axiom that the body is composed of the four elements 

 air, earth, fire, and water. From these the four fluids 

 or humours (namely, blood, phlegm, yellow bile, and 

 black bile) are formed. Health is the result of a right 

 condition and proper proportion of these humours, 

 disease being due to changes in their quality or distribu- 

 tion. Thus inflammation is regarded as the passing of 

 blood into parts not previously containing it. In the 

 course of a disorder proceeding favourably, these humours 

 undergo spontaneous changes in quality. This process 

 is spoken of as coction, and is the sign of returning health, 

 as preparing the way for the expulsion of the morbid 

 matters a state described as the crisis. These crises 

 have a tendency to occur at certain periods, which are 

 hence called critical days. As the critical days answer to 

 the periods of the process of coction, they are to be 

 watched with anxiety, and the actual condition of the 

 patient at these times is to be compared with the state 



