I enjoyed Amir Aczel's book in as much as it was a fairly well-written review of our current knowledge of the potential for intelligent extra-terrestrial life. However, Aczel is a professor of statistics, and perhaps in an effort to make his book stand out from the crowd, he ends with an unconvincing statistical argument that intelligent life must exist elsewhere. His argument boils down to this - we exist, therefore there is a chance of intelligent life evolving. Since there are so many stars in the known universe, it doesn't matter how small that chance is, because with so many stars there simply must be other intelligent lifeforms. Hmmm. Read the book, and judge for yourself!