This is a landmark publication in science writing. I came across Dr. Mayr`s work with his comprehensive volume “This is biology the science of the living world”. I read the German version when I just finished my study in biology and was on my Phd work in some more physics related area. Ernst Mayr gave me a drug. It was like a re-definition of my own subject that I came along when reading his book. My second text was his Magnum Opus (this book), which I bought in the English version where it was published first (although there is a translation now available). This is nothing less than a masterpiece and timeless reference on its subject. Of course, it bears the personal signature of the author and some people charge Mayr for his strong and sometimes even autocratical approach. Although the critics may be right at certain points, the clear and straightforward argumantation of Mayr and his incontestable knowledge accumulated in his long life, compensate by far and make this book a pleasure to read and an eyeopener to every person who is interested in the process of the development of scientific ideas. Biology is a self contained science, that is in some special parts different from other areas of what we call exact natural science. Everybody knows nowadays but it was not at least because of the pioneering work of Ernst Mayr that we can claim this to be a fact.