timothy from the sobering-thought-about-checks-in-general dept.
Barence writes "You may be aware of Donald Knuth, the creator of TeX and author of The Art of Computer Programming, who used to post checks to anyone who spotted an error in one of his books — one hexadecimal dollar, or $2.56. No one cashed them though. This blogger has two of them proudly on his wall, but the sad news is that modern day bank fraud has put a stop to Knuth's much-loved way of keeping his books free of errors." (Here's Knuth's own post about the sad change.)
You see but you do not observe.
Sir Arthur Conan Doyle, in "The Memoirs of Sherlock Holmes"