I've always been a fan of little Mercury since I read about the struggles Einstein had offering a proof of his General Theory. It had to do with photographing the transit of Mercury across the face of the sun during a total eclipse. The challenge led to 4 continents, unseasonable clouds (thus no photographs) and a World War until the deed was finally done and Einstein had his physical proof and the Nobel prize. Over 10 years was involved.

It turns out that there was much more to the story, which looks to be also the case with Mercury in the horoscope. Thanks for another great post explaining something mysterious to me.