138 SCIENCE REMAKING THE WORLD 



each produces its own peculiar results as product of its 

 life and growth. 



We need to recall that when Pasteur was studying 

 fermentation the human race did not know the causes of 

 human diseases. Causes had been suspected, but not 

 proved. What we know to-day as the science of public 

 health did not exist. The bacterial origin of diseases 

 was merely suspected, and the idea generally ridiculed. 

 If a person had been bold enough to assert as true even 

 a small part of what we now know to be true, such a 

 person would have been thought insane or foolish. It 

 was then not uncommon to think that persons who be- 

 came ill had been guilty of some gross wrong-doing, and 

 that illness was sent upon them as punishment for their 

 sins. Or it was sometimes said that the "humours of 

 the body," of which the blood and the bile were two, in 

 some way got into wrong proportions or became de- 

 ranged and thus caused illness. It is now generally 

 known that most, if not all, common diseases are caused 

 by living microscopic organisms, either bacteria or 

 small animal parasites. Though this knowledge is but 

 a few decades old, it is so common that it is difficult to 

 put ourselves back to the recent date when the human 

 race did not possess this knowledge. It is of such un- 

 told importance that Louis Pasteur lived and accom- 

 plished what he did, that, as we read this chapter, we 

 must imagine ourselves for a time moved back a little 

 more than forty years in the history of man's desire 

 and efforts to have better health. Then, as now, most 

 people wished to live instead of to die, and while living 

 wished to have the best possibk health. Then, as now, 



