You can imagine their disbelief. This almost certainly never crossed their minds. What kind of tank designer thinks about mouse protection? Nobody planned this,

You can imagine their disbelief. This almost certainly never crossed their minds. What kind of tank designer thinks about mouse protection? Nobody planned this, nobody expected it. But these things happen all the time. Risk does not like prophets. It’s not even fond of historians. You can plan for every risk except the things that are too crazy to cross your mind. And those crazy things do the most harm, because they happen more often than you think and you have no plan for how to deal with them. Risk in most professions is managed by studying what’s common. Maybe 10 topics and their solutions, said slightly differently, dominate business and investing books. The problem is that historical risks you can study are dwarfed by risks you actually experience. There are a zillion treacherous risks, but most on their own are not common enough to take seriously or collect data on. Like mice destroying tanks. Search the New York Times’ archives, and you’ll find that the word “unprecedented” has been published once for about every ten instances of the word “common.” Which is a lot. Stanford professor Scott Sagan nailed this when he said, “Things that have never happened before happen all the time.”