„The Riddle” contains Lem's short stories that do not belong to any of the „ordered” series. However, they are by no means marginal: some of them – such as „The Mask” or „Memoirs...” - belong to the most important of Lem's works. Questions raised in these stories – about the nature of being and consciousness – are fundamental and everyone must try to answer them in other to live an authentic life, to understand oneself and the world.