Ervin looks back at Watergate; The Whole Truth: The Watergate Consiracy, by Sam J. Ervin Jr. New York: Random House. $16.95

Robert P. Hey, now the Monitor's managing editor, features, reported on the Watergate hearings.

Two lawyers wrote this book: an analytical, Harvard-trained attorney, and a self-styled "country lawyer" who laboriously put everything down on legal-sized pads. They're the same man: former Sen. Sam J. Ervin of North Carolina.

It's a fine book for anyone who wants to read the important results of months of Watergate investigations boiled down into 300 readable pages. It's logically organized, clearly written, and highly informative for the average reader. And it's sprinkled with the leaving, down-home phrases for which Senator Ervin has long been known.

The problem is the book's timing is lamentably poor. Most people don't want to read about Watergate today. The naion has moved past Watergate -- its attention is focused elsewhere.

There's reason for this poor timing. Senator Ervin explains that originally he didn't intend to write about the Senate Watergate committee investigation he chaired -- nor about other aspects of Watergate, either. Then he read former President Richard Nixon's memoirs, felt them grossly inaccurate about Watergate, and decided to write his own book to set the record straight.

What he wrote chronicles the changes in his view of the former President. When he first became chairman of the Senate committee he considered it "inconceivable . . . that President Nixon was personally involved in the cover-up operations." What he learned caused him ultimately to conclude the opposite.

Unfortunately, timing isn't the only lost opportunity of "The Whole Truth." There's very little light shed on the inner workings of an important, influential committee and its dramatic hearings. It would have added dimension, especially at this late stage, to have shed light on the process of Democracy at work, as well as on the result.

In any case the book offers the reader an important and hopeful view of a difficult time. "Watergate," the senator reminds us, "has a positive aspect, which ought to give Americans confidence . . . it proved our Constitution works."

He quotes Shakespeare: "Sweet are the uses of adversity, Which, like the toad, ugly and venomous, Wears yet a precious jewel in its head."