NONFICTION : THE SECOND OLDEST PROFESSION by Phillip Knightley (Norton: $19.95; 436 pp.).

This is a skeptical look at the value of spies and the leading national intelligence organizations in the 20th Century. The author, a writer for the London Sunday Times, is convinced that billions of dollars have been wasted by the major world powers sustaining such organizations, which he maintains have been, for the most part, almost useless.

“Like the spies who work for them, these clubs have much in common,” Knightley writes. “Each owes its survival to the existence of its fellows. What would the CIA and (Britain’s) SIS do without a KGB, and vice versa? Each has helped create the state of tension in which all thrive. All feel threatened by detente. All have a direct interest in the continuation of the Cold War.”

Not only do the spy organizations serve to exacerbate tensions and discourage attempts to improve relations between the super powers, he concludes, but they are not nearly as proficient in gathering secret information as their often self-inspired legends indicate. And when they do succeed in conveying a warning, or valuable information, they are usually not believed.

Sweeping conclusions, but a great deal of historic evidence is amassed here to support them. Those who belong to the intelligence-gathering services won’t like this book. For the millions who are paying their bills through taxes, it may well give considerable pause.