This book is an attempt to correct and develop the theory proposed tentatively in the little work Malaria. Put briefly, this theory is as follows. In the struggle for existence man has competed, not only with his fellow-men, but also with wild animals and disease- parasites. The fight against beasts was decided long before the historic period, but parasites have always been, and still are, formidable opponents. Whole tribes have been wiped out by plague, kala-azar and measles; and even when the disease-parasite does not win such a decisive victory, it often weakens a nation so much that the latter falls an easy victim to its healthier neighbours. This volume will show how malaria played a part in the decline of the ancient Greeks, along with statistics presented from the Greek Anti Malarial League, and evaluation of malarial literature. (Summary by Leon Harvey)