"This latest book by Raymond Smullyan follows a similar format, offering a mixture of interesting puzzles, "monkey tricks" designed to catch the reader out, dreadful jokes, and insights into serious mathematics. If you have enjoyed Smullyan's previous books this one is self-recommending." London Mathematical Society Newsletter "A reader without prior experience with mathematical logic would likely benefit from having done the logic puzzles in the first half of the book before tackling the second half. I have found it useful source of enrichment activities, though, and if you are a fan of Smullyan's other works, you will find much to enjoy here." MAA Raymond Smullyan presents a bombshell puzzle so startling that it seems incredible that there could be any solution at all! But there is indeed a solution — moreover, one that requires a chain of lesser puzzles to be solved first. The reader is thus taken on a journey through a maze of subsidiary problems that has all the earmarks of an entertaining detective story. This book leads the unwary reader into deep logical waters through seductively entertaining logic puzzles. One example is Boolean algebra with such weird looking equations as 1+1=0 — a subject which today plays a vital role, not only in mathematical systems, but also in computer science and artificial intelligence.