MORGAN GOWER, THE HERO of Anne Tyler's latest novel, is a man of many parts. A 42-year-old paterfamilias with the feckless charm of Peter Pan, an all-American elf capering through all available social personas, Morgan becomes a shoemaker the moment he enters a shoemaker's shop, a mailman when he stands by a mailbox, a Frenchman when he puts on a top hat, a Jesuit priest, a jockey. He is the spirit of romancing. He lives in a lovingly catalogued profusion of his own cast-off disguises and strata upon strata of his immensely extended family's scatterings, hankering vainly all the while for order and barbones simplicity. Here he is, writing a letter of advise to his newlywed daughter: "Dear Amy,

"I notice that you appear to be experiencing some difficulty with household clutter.

"Understand that I'm not blaming you for this, your mother has the same problem. But as I've been telling her for years, there is a solution.

"Simply take a cardboard box, carry it through the rooms, load into it everyone's toys and dirty clothes and such, and hide it all in a closet. If people ask for some missing object, you'll be able to tell them where it is. If they don't ask (now, here is the important part), if a week goes by and they don't notice the object is gone, then you can be sure it's non-essential, and you throw it away. You would be surprised at how many things are non-essential. Throw everything away, all of it! Simplify! Don't hesitate!"

As his tale unfolds, Morgan undertakes to follow these precepts as he yields to the fascination of Emily Meredith, a young married woman whom he meets at a church bazaar where she is manipulating a hand-puppet of Cinderella. Instead of fleeing the ballroom as the clock strikes 12, Cinderella faints: Emily is about to give birth. Morgan, the eternal imposter, answers the call for a doctor in the house and delivers her child. In the years that follow Emily becomes an emblem for Morgan of that spartan order he longs to bring to his over-furnished life. Emily is an orphan. She lives with her husband and child in an apartment amost devoid of possions. Her ambitions are as limited and unchanging as her basic black wardrobe of leotards and mid-calf skirts. Inexorably these polar opposites attract each other with results that are chilling, heartwarming and hilarious.

In the paradoxical character of Emiy, at once passive and inflexible, ruthless in her rejections and unswerving in her loyalty, Tayler has created the kissing cousin to Charlotte Emory, the heroine of he last novel, Earthly Possions . Both women achieve spirital freedon in circumstances of poverty and psychological subjection; both are dutiful victims, not of the sexist gargoyles grimacing from the pages of so many recent novels, but of entirely ordinary men of limited competence and probity. Because "average" people don't usually make for large drama or high comedy, they are much less common in fiction than in real life. Perhaps it is Anne Tyler's most uncommon accomplishment that she can make such characters interesting and amusing without violating their limitations.

Happily, despite the novel's portending title, Morgan survives his reordering, not wholly intact but in all his essentials, and one finishes the book with a quiet hurrah for human nature. Not since Garp have I come across a character in a recent novel who is at once so plausibly flawed and so improbably lovable.

Like Garp, Morgan is surrounded by an entire commedia dell'arte company of supporting players: a brilliantly "senile" mother; a Sarah Gampish unmarriageable sister; a moneyed wife as careless and iron-willed as an empress; in-laws, uncles, aunts, and, underfoot everywhere, the children. For, like Garp, Morgan is essentially a family man, a house-husband. His wife's family has given him a job tending one of their hardware stores, but that's all a fiction. His real work is siring children and enlivening the lives of those about him with the gifts of his imagination: like Garp, he is an artist.

Let us have Morgan speak for himself. Here he is, with his wife Bonny, as they explain to Emily his theory of what makes him tick:

"'it's a matter of muscles,' he said, ". . . A matter of following where they lead me. Have you ever gone out to the kitchen, say and then forgotten what for? You stand in the kitchen and try to remember. Then your wrist makes a little twisting motion. Oh yes! you say. That twist is what you'd do to turn a faucet on. You must have come for water! I just trust my muscles, you see, to tell me what I'm here for. . . . I let them lead me.'

" 'He lets them lead him into saying he's a glassblower,' Bonny said, 'and a tugboat captain for the Curtis Bay Towing Company, and a Mohawk Indian high-rise worker. . . . You're walking down the street with him and this total stranger asks him when the International Brotherhood of Magicians is meeting next. You're listening to a politician's speech and suddenly you notice Morgan on the platform, sitting beside a senator's wife with a carnation in his buttonhole. You're waiting for your crabs at Lexington Market and who's behind the counter but Morgan in a rubber apron, telling the other customers where he caught such fine oysters. It seems he has this boat that was handed down from an uncle on his mother's side, a little bateau with no engine--'

" 'Engines disturb the beds,' said Morgan. 'And I don't like mechanical tongings rigs, either. What was good enough for my uncle on my mother's side is good enough for me I say.' "

The flavor of the book is alternately lyrical and rambunctiously comic -- as though Chekov were to rewrite one of Kaufmann and Hart's comedies ofconfusion; as though Flannery O'Connor were to forget all about religion and write a whole novel as droll as her tales; as though Dickens were alive and well and living in Baltimore.

But even those wild hyperboles tell only half the story -- Morgan's half. Emily, who has almost as much time center stage, is a quieter presence (quite literally, having been brought up a Quaker) but no less vivid. Her diffident devotion to the plainest truth reflects a similar bedrock simplicity in Tyler's prose -- the other side of the coin to Morgan's (and his creator's) ebullient profusions. The effect of this synthesis is a totally believable fictive world with the concrete reality of a Manet and the radiant colors of a Matisse.