Caliban is a Shakespearean character taken from The Tempest by William Shakespeare.    Caliban is a half-monster man: his face is ugly and deformed like a monster. Oscar Wilde quote Caliban in The Preface of The Picture Of Dorian Gray. The horrible physical appearence of Caliban suggests to Oscar Wilde a different point of view of Realism.
The mirror reveals to Caliban his true face. Caliban gets angry for his deformed face. According to this concept, the Realism is the mean by which mankind looks for reality. Most of times Realism reveals an unexpected or unwanted reality. For this reason the XIX century looks with contempt to Realism movement as Caliban refuses the mirror.
On the other hand Caliban's refusal to look himself in the mirror evokes a sense of incompleteness and angry: Caliban will not know what face he has, he will not know the reality. According to this concept the XIX century dislikes the Romanticism because it does not reveal reality.
In conclusion the nineteenth century refuses both Realism and Romanticism due to their incapacity to reveal a reality that pleases men.