Christopher Columbus was at a party with Spanish nobles when he found himself having to defend his reputation. It was inevitable, he was told, that someone would have discovered the New World if he hadn’t done so.

In response, Columbus asked for an egg to be brought to the table, and challenged the nobles to make it stand on its end. After they had all tried and failed, Columbus tapped the egg on the table, cracking the bottom slightly so that it did not fall over; demonstrating that while his idea was straightforward, the challenge was to think of it in the first place.

At least, that’s the story according to the Italian merchant and historian Girolamo Benzoni, who was writing 60 years after Columbus’ death. Another version, written by Renaissance biographer Giorgio Vasari, appe...