 So what were the odds of seeing a black swan at that time? Impossible to calculate, but considered impossible until 1697 when explorers found a black swan in Australia. Imagine that. They had a black swan event, finding black swans in Australia, when it was considered impossible. We had a black swan event in 2001, didn't we? 9-11. And we are having many others these days. Earthquakes, volcanoes, terrorist strikes, and so on.