Reading these books in the order they were written has been an intriguing peek into the life of the author as well a satisfying plunge into a good story. Having written the series over the entire course of his life, Asimov’s interests and values changed and grew richer, and the books reflect this. The wonderful concept of a mathematical model of collective human behavior is a constant through all of the books, but they explore it from a wonderfully diverse set of perspectives. The early books are largely concerned with political and historical forces. The importance of the emotional component of the human psyche is explored. The cultural background reflects a conservative, male-dominated society. These values change radically in later books. Asimov clearly become more interested in human sexuality, variances and constants among different cultures, computers, robots, the Gaia Principle, and martial arts, just to name a few. It’s joy to accompany him on that journey as well as the journey of the inhabitants of his future galaxy.