In first place, and it's not even close: Martin Gardner's Scientific American columns. I can't believe they haven't been mentioned yet. They're (slowly) being r

In first place, and it's not even close: Martin Gardner's Scientific American columns. I can't believe they haven't been mentioned yet. They're (slowly) being reprinted by Cambridge, or you can buy a CD with all of them. Now the rest. One lesser-known book that made a deep impression on me: A.K. Dewdney's "The Planiverse", a kind of Flatland-meets-the-MIT-hackers story. How would architecture, biology, and chemistry work in a 2-dimensional world? Sagan's "The Demon-Haunted World" was an important book for me, but I read it when I was a couple years older than 14. SICP, if the 14-year-old knows basic programming and has written a few 1000-line programs. I wouldn't have understood it at 14 but enjoyed it tremendously at 18.