In Memoriam Jun John Sakurai was born in 1933 in Tokyo and came to the United States as a high school student in 1949.He studied at Harvard and at Cornell, where he received his Ph.D.in 1958.He was then appointed assistant professor of Physics at the University of Chicago. and became a full professor in 1964.He stayed at Chicago until 1970 when he moved to the University of California at Los Angeles,where he remained until his death. During his lifetime he wrote 119 articles in theoretical physics of elementary particles as well as several books and monographs on both quantum and particle the The discipline of theoretical physics has as its principal aim the formulation of theoretical descriptions of the physical world that are at once concise and comprehensive.Because nature is subtle and complex,the pursuit of theoretical physics requires bold a and enthusiastic ventures to the frontiers of newly discovered phenomena.This is an area in which Sakurai reigned supreme with his uncanny physical insight and intuition and also his ability to explain these phenomena in illuminating physical terms to the Mechanics as well as his reviews and summer school lectures to appreciate this.Without exaggeration I could say that much of what I did understand in particle physics came from these and from his articles and private tutoring. When Sakurai was still a graduate student,he proposed what is now known as the V-A theory of weak interactions,independently of (and simultaneously with)Richard Feynman,Murray Gell-Mann,Robert Marshak,and George Sudarshan.In 1960 he published in Annals of Physics phetic paper,probably his single most important one.It wascon erned with the first serious attempt to construct a theory of strong interactions based on Abelian and non-Abelian (Yang-Mills)gauge invariance.This seminal work induced theorists to attempt an understanding of the mecha- nisms of mass generation for gauge(vector)fields.now realized as the Higgs mechanism.Above all it stimulated the search for a realistic unification o forces under the gauge principle,now crowned with success in the cel- ebrated Glashow-Weinberg-Salam unification of weak and electromagnetic forces.On the phenomenological side,Sakurai pursued and vigorously advocated the vector mesons dominance model of hadron dynamics.He was the first to discuss the mixing of and meson states.Indeed,he made numerous important contributions to particle physics phenomenology in a