This volume of essays is dedicated to Professor Elliott Waters Montroll on his sixtieth birthday. The outstanding scientific work of Professor Montroll, his record as a teacher, lecturer and director of research, his active role on numerous governmental, academic and industrial advisory boards and panels, his editorial endeavors and the long line of students, collaborators, colleagues and friends are all a testimony to his con- tributions to science and society.
Characteristic of Montroll are his fascination with the world, and the continuous search for systematics and patterns of behaviour of physical and social systems. This search is assisted by his creativity, vast knowledge of physical and mathematical methods and his elegance of exposition. Montroll is a dedicated collector of many "things", ranging from data, facts and historical sources to books, coins, stamps and old prints. This blend of knowledge and the relentless quest for understanding guided his search for broad schemes governed by fundamen- tal principles, which would enable the systematization, quantification and prediction of complex phenomena and behaviour of convolved systems. This motto is best stated in the Preface to his book (co-authored with W. W. Badger), "Introduction to Quantitative Aspects of Social Phenomena":
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