Despite being written nearly a century ago, and suffering from some peculiarities of the author's simplistic conception of religious psychology, this book remains the best general introduction to its subject that I have read. At its best - and it is very frequently at its best - Nilsson surveys a millennium of Greek religious belief with confidence, combining findings in history, archaeology, and the study of ancient literature in a remarkably resilient interpretive picture which has stood well through the long years. For example, he speaks of the likelihood that Athena was known to the Myceneans, and in fact, we now know that she was, as she is attested in certain Linear B writings. Likewise, when he describes waves of immigration that comprised the peopling of Greece with confidence, we can now agree with his model, as it is consistent with the genetic evidence.
These things incline me to take his historical arguments seriously, and they are of great significance for understanding the character and development of Greek religious thought. Nilsson persuasively argues, for example, that the period in which the core myths and stories of Greek religious culture were formed was the late Bronze Age, and as evidence he surveys the occurrence of major population centers that feature in Greek myths, and finds that they correspond with the major population centers of Greece of that period.
I was disappointed by the author's facile religious psychology, which understands myth primarily as stories that provide explanations for difficult-to-understand events and phenomena. That is indeed one of a great many functions of myth, and to me the lowest in importance and the least-interesting. Nevertheless, it is a valuable and informative book.