Sergey Brin watches a smaller mind — that of Akamai chief executive, Paul Sagan — wrestle with a puzzle at a geek dinner at the Davos conference, earlier this year. The challenge, using three knives, build a bridge spanning three wine glasses, one strong enough to support a bottle. In this clip, below, the Google founder watches, rather stiffly, as if he's bursting with the answer, and is holding it in; or else he's terrified that he'll be put on the spot himself, and struggle. Now how embarrassing would that be.

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