from the flesh of rotten calves and oxen, wasps and hornets 
from that of rotten horses, and beetles from that of asses; 
foolish as it appears, to believe that an infinite number of other 
insects are produced from cheese, from different plants and 
even from mud; it has required a great deal of observing and 
of reasoning before it became possible to confute these absur- 
dities. Even in our days, some men, illustrious by their learn- 
ing, were possessed by such vagaries; for instance the famous 
Father Kircher and Bonnani, although natural history owes a 
great deal to them. As late as 1717 a work was published in 
Venice, entitled: Motivi di dubitar intorno la generazione de’ viventi 
secondo la commune opinione de’ Moderni, in which an attempt. is 
made te resuscitate the old error. 
It is a matter of surprise that such ideas should have 
continued to prevail at a time when students had already begun 
to consider with a philosophic eye the smallest of insects. 
They must have soon become aware that the mechanism of 
the different organs which constitute the body of a moth, is 
not less complicated than that which is found in the body of 
an elephant. Philosophy must have taught them that the con- 
ceptions of great and small exist in our minds only, and in rela- 
tion to ourselves, and that, for this reason, the structures of 
almost imperceptible insects are in reality just as admirable as 
those of animated masses of colossal size. The evolution of 
the smallest animalcules requires as many preliminary processes 
as that of the largest animals. And it is just as ridiculous to 
believe a fly to be born from a rotten carcase, or an oyster 
from a handful of mud, as to expect an ox, or an elephant, to 
emerge from a rotten haystack! 
As long as nature had not been sufficiently studied, those 
who saw worms crawl out of decaying flesh, quite naturally 
believed that these worms originated in it. The observations 
made by Redi, and lately by Leeuwenhoek, curious in them- 
selves, were indispensable for enlightening those, whose mind 
could only perceive what was conveyed to it by their bodily 
eyes (,dont Vesprit ne voit que ce qui lui a été transmis par 
