Kosaku Yosida is world famous as the founder (together with Einar Hille) of the theory of semigroups. These collected papers provide valuable information on how he started and developed functional analysis and operator theoretical methods in the theory of differential equations and probability theory. The book is divided into 10 sections following the main topics on which Yosida worked. Each section includes comments by a specialist of this field for the benefit of the reader. An extensive bibliography both of all Yosida's English and Japanese papers is included. This edition will prove invaluable to anyone wanting a comprehensive view on Yosida's work.