INTRODUCTION XI 



and why it is that a man who understands the laws of growth 

 and of inheritance may, in a very real way, drive the crippled 

 Fates from the field and help shape the future of the race. 



Some one has suggested that the three Fates of modern 

 life are 



1 . Heredity — what we receive from our ancestors by the 

 road of inheritance. 



2. Environment — all that surrounds us and influences us 

 from the cradle to the grave. 



3. Personal choice or will power — what we make of 

 ourselves during life. 



The analogy is not altogether perfect, but the following 

 pages take each of these modern Fates into account. 



To understand inheritance we must follow life from pre- 

 historic ages until now. From small beginnings we must trace 

 large results — must learn how it is and why it is that all life 

 on the earth is joined as a unit, and must know how life is 

 passed on from generation to generation. 



We must even study life cells in their development, and 

 watch them as they grow from stage to stage, until at last 

 they become well-developed beings. 



In other words, we must learn so many facts about life itself 

 and about what controls it, that we shall be better prepared to 

 face our own lives and the lives of future generations. 



Science says human beings will be safer when people 

 know the facts and are influenced by them. Teachers say, 

 " Give us the facts and we will pass them on to the boys 

 and the girls whom we teach." Both scientist and teacher 

 agree that the human race will be better able to escape 

 certain kinds of peril if we let young people know what the 

 perils are and how to avoid them. 



Such is the purpose of this book. 



