THE BOOK OF SORROWS by Walter Wangerin Jr. (Harper & Row: $15.95) concludes the account, begun in 1978's "Book of the Dun Cow," of how the animals of rooster Chauntecleer's once-idyllic Coop manage to survive their war with that embodiment of evil, the serpent Wyrm. If Indiana clergyman Wangerin's prose is much more demanding here--indeed, self-consciously elegant to the verge of pompousness--it's also notably more gorgeous (Consider, for example: "And so descends the evening . . . the sky so sadly purple, a bruise in the universe"), by turns hilarious, uplifting and heartbreaking. "You are God's kindest thought," the vengeance-obsessed Chauntecleer tells his wife, Pertelote, in a rare rational moment, and with ample reason. But the saintly hen is no kinder, no more selfless nor loving, than a dozen other of Wangerin's characters. As adeptly as he breaks the reader's heart, he warms it over adeptly still, evoking the most tender emotions as vividly as one is likely to find them evoked in American fiction. In the process of trying to avenge the deaths of two loyal friends, the Ahab-like Chauntecleer engenders vast anguish, but comes ultimately to see that he was wrong to have concluded that "love is a deception." His arrival at this realization is jarringly sudden and jarringly unconvincing. But oh, the getting there!