The kind of novel that earned Oe his Nobel Prize

The 3rd short novel in the 1977 collection of 4 from Kenzaburo Oe gives the collection its title, Teach Us to Outgrow Our Madness (the novel suggests that this is a phrase from a poem by one of the British poets of WWI, Owen or Brook perhaps?); as noted previously, I'm reading these short novels in order of publication/composition, not order in this collection, which offers little guidance on publication dates. This one is the saddest so far and is clearly based on the central fact of Oe's life, the birth of his son w/ severe brain damage and consequent mental retardation. In this work, the protagonist, referred to only as the Fat Man, has a caring and loving relationship w/ his son; the two go out for lunch - same place, same order - every day and take excursions that his son - who's maybe about 4 or 5? - enjoys, notably to the zoo. It's hard at times to piece the narrative together, but it seems that at one point some nasty guys grab the Fat Man and pretend to toss him into the polar bear exhibit; meanwhile, the on wanders off - crisis ensues, all sad and troubling. In another episode, the son goes to a specialist for an eye exam and creates havoc in the office - he's strong and stubborn and extremely disturbed when anyone touches him, let alone examines his eyes. All of these, and other, trying episodes split marriage, leaving the Fat Man alone with his obsessions: He is struggling to write a biography of his father, who spent the last years of his life self-imprisoned in a storage locker, until he committed suicide. So this strange novel involves mental illness and brain damage across several generations and is, intentionally, upsetting and challenging (told out of sequence and sometimes from a perspective of limited vision and comprehension), though we cannot help but feel sorrow and pity for the man, so devoted to his son, and to the poor child, suffering without understanding. This is the kind of work that later earned Oe his Nobel Prize.