Darwin’s theory of natural selection issued a profound challenge to orthodox thought and belief: no being or species has been specifically created; all are locked into a pitiless struggle for existence, with extinction looming for those not fitted for the task. 

Faculty Comment: John Colicelli 
It is fascinating to follow Darwin’s methodical march through the evidence for “descent with modification”, written long before DNA was identified as the cell’s genetic material. Reading even a single chapter will leave you with a better understanding of this revolutionary theory and its most notable proponent.