XIV 



In this search, we therefore offer an account of the state of our 

 knowledge, our hopes, and our puzzles as they are today. We hope 

 the material will convince the reader how fascinating and how timely 

 is this topic in the present state of science. We might remark also that 

 a focus on the widespread but rather quiet, cryptic life of the 

 microbial mats of the great watery flats is strangely relevant to 

 today's world in which the geochemical and atmospheric cycles 

 themselves begin to show the effects of human intervention for good 

 and bad. The great role of that lowly life in the deep past is to a 

 degree continued today; we know all too little of its complex and 

 rich operations within the changing balance of contemporary nature. 

 As we look back into the past, we will both employ and illuminate 

 the present. But above all, what we seek is not only practical advan- 

 tage, though that will come. Our chief goal is a kind of self- 

 knowledge, as deep as our oldest myth: how it came about on this 

 Earth that the quick were first parted from the dead. 



Philip Morrison 



Massachusetts Institute of Technology 



Cambridge, Massachusetts 



