Anthony Burgess points out that pornographic works
encourage solitary fantasy, which is then usually quite harmlessly discharged in masturbation. A pornographic book is an instrument for procuring sexual catharsis, a substitute for a sexual partner.
If we read a book or see a play or film
and are driven to discharge the aroused emotion in some solitary or social act, we have experienced good pornography or good didacticism but bad art — an instrument of stimulation masquerading as a work of art. Pornography is harmless so long as we do not corrupt our taste by mistaking it for literature.