54 THE MEANING OF EVOLUTION 
Charles Darwin, humanly speaking, may be ac- 
counted for as the happy combination of a double 
heredity and a favorable environment. He inherited 
the scientific inclinations of his grandfather, Erasmus 
Darwin, and the patient, sturdy honesty of his other 
grandfather, Josiah Wedgwood. These developed 
under the stimulus of the long five-year voyage, face 
to face with the world of nature. This happy com- 
plex produced the master biologist. To believe that 
he came about purely by chance requires a great 
stretch of the imagination. “There’s a divinity that 
shapes our ends.” 
We have endeavored to make clear two of the basal 
ideas underlying evolution. One of these is respon- 
sible for the continued production of animals or plants 
of the same kind, preventing the world from becom- 
ing a wild kaleidoscopic and fantastic dream. Hered- 
ity is the conservative force of nature. The other idea 
underlies the development of new departures which 
keep the world from being a dull, dead, unending 
repetition of the same monotonous material. Varia- 
tion is the progressive tendency in nature. 
The third basal idea is that of Multiplication. Ani- 
mals and plants multiply; they do not simply increase, 
they increase in a geometrical ratio. Anyone who 
has worked out one of these geometrical ratios knows 
how wondrously they mount up. There is an old fa- 
