The trouble with being a professional actor is that no one knows whether you're acting or not.

		"ELEGY FOR SAM EMERSON" By Hilary Masters. Southern Methodist University Press ($23.95)

In Hilary Masters' new novel, Sam Emerson has this problem with his mother, who is confined to a nursing home, but once was an actress a couple of strobe-light flashes less than a star.

He would slip a tape into the machine, and say, " 'Let's have a little music.' ... 'Oh, yes, let's do have music,'" she would respond, clapping her hands, her eyes becoming brilliant, as if footlights had suddenly come on at the foot of her bed."

In fact, as Sam sees it, Edie's entire life was a reality show, purposeful, and only partly ad-libbed. His father was a war photographer (although he excelled at the kind of peace-time pictures he never had a chance to take) and traveled most of the time. Between the two, Sam felt like a child run over by his parents on their ways to careers.

Raised in Ohio by his Auntie Rho (who remains puzzlingly generic until the very end of the book), he kept his deepest affections and most uncritical appreciation for those pleasant times in East Liverpool.

Now Sam has grown up to become a partner in an upscale Pittsburgh restaurant named Sam's Place. He is one of the more appealing figures to show up yet in a contemporary novel written in an era of lethal post-modern ironies.

Divorced and in love with a considerably younger woman, unsure of their future together and engaged in the double quests of the plotline -- a place to deposit Edie's ashes, and the years-long search for his father's military grave -- Sam turns out to be a healthy, happy, hopeful, well-meaning man.

This is so unexpected in such a book, you have to love him for it, as his girlfriend Phoebe, a "licensed counselor specialist in addictions," does. Whether he gets what the reader thinks he deserves is beyond the radar of the book, but you'll desperately hope so.

On the other hand, his boyhood friend Teddy, who has grown up into a posturing journalist, takes care of the more sophisticated chores, providing a snapshot of the cultural zeitgeist of our time. Still, even he (Masters is a compassionate novelist) has his redeeming vulnerabilities.

Unless I missed something, the title is a trifle misleading; more appropriate, perhaps, would be something like "Elegies by Sam Emerson."

The need to come to terms with the dead forms the heart of the novel, and in order to do this he must review his past. The story is made up of almost equal-time accounts of Sam's current life in the 1990s and the personal history from the 1940s and '50s, rendered in present tense, that helped make him what he is.

Masters, honors-winning author of eight other novels, a memoir and short stories and essays, is professor of English and creative writing at Carnegie-Mellon University, and his love for the area is apparent.

He does justice to all the locales of this book (also including Ohio, New York and France), but his take on Pittsburgh makes it not so much another character as a personal ambience, a frame of reference necessary for the story and its characters.

Ardently described, Pittsburgh here is a particular, very beautiful part of America of a certain time and a certain place, never to be duplicated.

But Masters has a gift for reproducing vanished things and places as well, for instance, city buses, and the Automat in New York, as a boy sees it. And that's not to mention Paris's Notre Dame Cathedral, which he credibly imagines as a ship from outer space, too burdened by accumulated history to make the return trip.

As in all the best books of our time, this one harvests the human condition, and a rich haul it is. Readers will recognize it, for we have tended that crop ourselves.

Much of what is pleasing about this book concerns ideas (about race, human agony and what we do to survive) that are not fully expressed here in words so much as in vibrations, perhaps, or intimations, though more of mortality than immortality.

This is one of those rare books you will close with a satisfied sigh -- and you're not even quite sure why.