Anyone interested in the subject of unidentified aerial phenomena/unidentified flying objects and how the `problem' has been managed by governments and military authorities worldwide will know the names of J. Allen Hynek and Jacques Vallee. Both were trained professional astronomers: Hynek died in 1986 following many years working officially with the USAF on `Project Blue Book' and its various offshoots and Vallee, at the time of writing in August 2011, is still very much with us as a global authority in the development of IT systems and a successful San Francisco-based venture capitalist. Both were known as very sharp guys and somewhat out-of-the-box thinkers, each a published author with a substantial public profile. Both authors featured in Spielberg's 1977 blockbuster movie CE3: French film director Francois Truffaut played a character modelled on Vallee, and Hynek himself acted as a consultant to Spielberg and had a cameo part in the film.
This truly excellent book, published in 1975, features nine chapters mostly made up of insightful head-to-head debates between Hynek and Vallee about all aspects of the UFO issue, and moderated by Dr. Arthur Hastings. The ground covered is extensive and the level of discourse quite deep. Vallee summarises the puzzle of the phenomena nicely in the first chapter:
"We know there is an unknown phenomenon being manifested. It appears to centre on a technological device, a machine that is capable of transporting occupants. The behaviour of both the machine and the occupants appears to be consistent with the idea that we are faced with an alien form of life. However, their behaviour is not consistent either with what you would expect from space visitors, or with what we know about physics. That's the dilemma." (p25)
A couple of chapters examine a small number of cases personally investigated by the authors in great detail: the remarkable `Ely' case involving a long and complex UFO encounter by two brothers whilst driving a truck, resulting in severe and unexplainable damage to the truck; and the famous 1959 Boianai case at Goodenough Bay in New Guinea, involving communicative interaction between humanoid occupants of a large low-hovering disk with some 30 local people at a Mission School, including a RC priest. Discussion of these cases kicks off the interchange between the authors, and for the next 200+ pages the level of dialogue never disappoints, and is often thoughtful and enlightening.
It is instructive to re-read these conversations after the intervening decades, and especially enlightening to re-visit the authors' projections of `possible scenarios for the phenomenon by the year 2000'. As Vallee has said openly in interviews during the past couple of years, he's not really any the wiser about the issue now than he was in 1975, and most of these questions for him are still open.
Highly recommended to any reader or investigator who wants to engage with what is understood about these phenomena at a deep level, to consider the evidence and where it might lead in all its nuanced complexity from two of the smartest minds ever to focus on this elusive and puzzling subject.