A good introduction to Darwin's heavier tomes

THis little book is a pleasant and very interesting read even if you have not been a Darwin fan. Because his work was so seminal in changing the West's perception of evolution and how the world have developed and carries on developing new forms of old species, it is something that everyone and anyone who is at all interested in nature and humanity's place in it , should try to grasp. In this quite short book Darwin's seminal research is rendered more easily understood and easier to understand. So it is a good introduction to his "Origin of species" and the "Descent of Man". He also wrote "The Portable Atheist" which I am trying to find, and altogether he wrote 84 books! I have a lot of reading to do in a too rapidly diminishing time period!