This book is absolutely fundamental. It is brilliant and short. It should be read by anyone in any field. I cannot stress it enough. The title, of course, comes from Auden.
Dodds' father was friends with MacGregor Mathers and Stephan McKenna (the translator of Plotinus) and other 19th cen. Irish mystics. Dodds himself was a brilliant classical scholar.
He is best known for his Greeks and the Irrational
-- a book as fundamental as it is flawed (and his account of Plato IS flawed). This is ironic, since his commentary on the Gorgias of Plato is his best book. And it is a masterpiece:
http://www.amazon.com/Gorgias-Clarendon-Paperbacks-Plato/dp/0198144954/ref=sr_1_1?s=books&ie=UTF8&qid=1288146529&sr=1-1. The text is superb, and is an improvement on Burnet, and the commentary will never be surpassed. His judgement is flawless.
On gnosticism generally -- after reading Dodds' lectures - read Jonas, not Pagels. Yet another example of how modern scholarship proves that what is new is often not what is improved.
Anyway - consider this book as most HIGHLY recommended to anyone who chances on this review.