One of the points clearly stressed in the beginning of this book is that the essential feature of any dynamic system is change and that, where there is change, there may also be growth and evolution. Plant breeding and plant protection have grown and evolved considerably during the past century; they have also witnessed several, important Hegelian changes. This book, by R.A.Robinson, is just such a change in scientific thinking. It is unique in presenting an entirely new insight to plant-parasite relationships, and in providing a practical guide for managing plant pathosystems for man's advantage in agriculture. The author brings together for the first time in a holistic manner the various plant protection and breeding disciplines; he analyses their past limitations and deficiencies and throws useful new light on the nature of parasitism. From this he is able to gain a clear understanding of the functions of the various pathosystem components. On the basis of this understanding he then proposes practical ways for using these components to achieve and maintain the type of balance which is the basis of survival in any evolutionary system, including that of man himself. All this is done in a lively and elegant manner, using logic as the main driving force to elucidate and define entirely new concepts without obstruse mathematical or biochemical formulae.