Citation de Bookycooky
I remember a joke about a mathematician, a physicist, and an engineer riding a train in Scotland. Looking out of the window, the engineer sees something that catches his eye. Look, he says, it’s a black sheep! It seems the sheep in Scotland are black. The physicist shakes his head. Nonsense, he says. All we know is that there are some black sheep in Scotland.The mathematician looks at his two friends, sighs, and with all earnestness observes: All we can say is that there is at least one sheep in Scotland, one side of which is black.
