380 THE CAUSES OF THE XI 
acid, and others, have been added to the list. I 
need not tell you that chemistry is an enormous 
distance from the goal I indicate; all I wish to 
point out to you is, that it is by no means safe 
to say that that goal may not be reached one 
day. It may be that it is impossible for us 
to produce the conditions requisite to the origina- 
tion of life; but we must speak modestly about 
the matter, and recollect that Science has put her 
foot upon the bottom round of the ladder. Truly 
he would be a bold man who would venture to 
predict where she will be fifty years hence. 
There is another inquiry which bears indirectly 
upon this question, and upon which I must say a 
few words. You are all of you aware of the 
phenomena of what is called spontaneous genera- 
tion. Our forefathers, down to the seventeenth 
century, or thereabouts, all imagined, in perfectly 
good faith, that certain vegetable and animal 
forms gave birth, in the process of their decom- 
position, to insect life. Thus, if you put a piece 
of meat in the sun, and allowed it to putrefy, they 
conceived that the grubs which soon began to 
appear were the result of the action of a power of 
spontaneous generation which the meat contained. 
And they could give you receipts for making 
various animal and vegetable preparations which 
would produce particular kinds of animals. <A 
very distinguished Italian naturalist, named Redi, 
took up the question, at a time when everybody 
