[Detached from common sense the analytical approach in philosophy can easily lead even the most brilliant minds into silliness, as the following incident shows.]
Probably the two most famous philosophers of the twentieth century in the English speaking world were Bertrand Russell and Ludwig Wittgenstein. In 1911 the 39 year old Russell tried to get the 22 year old Wittgenstein to accept the proposition: There is no hippopotamus in this room at present. When Wittgenstein refused to believe this Russell looked under all the desks without finding one. Nevertheless, Wittgenstein remained unconvinced.