It is the banal gritty thing

"What happens if we try to apply this classical Aristotelian canon to a modem work like Joyce’s Ulysses, 734 pages of power and dullness, beauty and sordidness, comedy and pathos, where the movement is always horizontal, never ascending toward any crisis, and where we detect not the shadow of anything like a climax, in the traditional sense of that term? If Joyce’s had been a disordered mind, we could dismiss all this as a sprawling chaos; but he was in fact an artist in superb control of his material, so that the disorder has to be attributed to his material, to life itself. It is, in fact, the banal gritty thing that we live that Joyce gives us, in comparison with which most other fiction is indeed fiction. This world is dense, opaque, unintelligible; that is the datum from which the modem artist always starts." (Irrational Man, William Barrett) http://www.philosophymagazine.com/others/MO_Barrett_Irrational.html

Could you please help me to understand the blue sentence?

Cadzao