512 STRUCTURE AND LIFE HISTORIES 
fear, wherever it might lead them, or however much it 
might contradict all their prejudice and preconceived 
notions. But truth will always, in the end, command 
recognition and acceptance, and there is almost no scien- 
tific man, now-a-days, who does not regard evolution as 
axiomatic. It is one of the most basic of all conceptions, 
not only in the natural and the physical sciences, but also 
in history, sociology, philosophy, and religion; it has, in- 
deed, completely revolutionized every department of 
human thought. 
441. Darwinism. It is the second of the above men- 
tioned theories, i.e., natural selection, that constitutes the 
essence of Darwinism. The theory is based upon five 
fundamental facts, which are matters of observation, and 
may be verified by anyone, as follows: 
1. Inheritance. Characteristics possessed by parents 
tend to reappear in the next or in succeeding generations. 
We are all familiar with the fact that children commonly 
resemble one or both parents or a grandparent, or great 
grandparent in some characteristic. From this we infer 
that something has been inherited from the ancestor which 
causes resemblance in one or more characters physical or 
mental. 
2. Variation. But the expression of the inheritance is 
seldom, if ever, perfect. Eyes are a little less or a little 
more brown; stature is never just the same; one-half the 
face may resemble a given ancestor more than another; 
petals may be more or less red or blue; no two oranges 
taste exactly alike; no two maple leaves are of precisely 
the same shape. There is inheritance, but inheritance is 
usually expressed with modifications or variations of the 
ancestral type. 
