Whosoever wants to portray something that does not exist has to obey certain rules. Those rules are more or less the same as for the teller of fairy tales: he has to apply the function of contrasts: he has to cause a shock.
The element of mystery to which he wants to call attention must be surrounded and veiled by perfectly ordinary everyday self-evidences that are recognizable to everyone. That environment, which is true to nature and acceptable to every superficial observer, is indispensable for causing the desired shock.
That is also why such a game can be played and understood only by those who are prepared to penetrate the surface, those who agree to use their brains, just as in the solving of a riddle. It is thus not a matter for the senses, but rather a cerebral matter. Profundity is not at all necessary, but a kind of humour and self-mockery is a must, at least for the person who makes the representations.
MC Escher 1958