The Fact of Evolution
This is a book about life - life that continues from generation to generation, life that exists in a variety of forms surpassing human imagination, life that changes to meet changed conditions, life that slowly advances through time so long that we can hardly grasp it.
Life is not a special force. In one sense, it simply means all living things. In another sense, it means the properties of living matter - the ability to use other matter as food, to respond to outside stimuli, to grow, to organize itself in particular patterns, to reproduce - and to change and evolve.
Man is the only creature that has been able to find out how many distinct kinds of living things, or species, exist. He has reached about a million and a half, and is still discovering new ones.
In this book, we will consider how all the different forms of life are related, how life changes with time, how it produces its amazing variety, how it advances. In other words, this is a book about evolution.