What is the reason for the huge success of the novel, ‘The Name of the Rose’?

‘The Name of the Rose’ is a very serious novel. At one level, it is a detective story. At the other level, it also delves deep into mythology and metaphysics. It is set in a period of medieval history. Of course, there are people who like serious reading material. Yet, the huge popularity of the novel remains a mystery. Perhaps, the time of its publication was favourable.