Dr. Ruth at her most inimitable, dispensing advice on married sex rather like a favorite auntie sharing her kugel and poppycake recipes with a young couple. She tosses her ingredients about with gay abandon, starting out with the question, ""Why a New Marriage Manual?"" Answer: Marriage is coming back in style. Then there's a chapter defining what sexuality consists of, followed by one discussing various fantasies about marriage, evidently culled from her practice as a sex therapist and from her radio and TV shows. At last: the wedding night. Most of this chapter is concerned with advice on how to deflower a virgin bride. ""Virgins,"" says Dr. Ruth, are ""a fact of life."" And so she goes, chapter by chapter, extolling the virtues of communication, sexual fantasies, morning sex, masturbation; also dissertations on the clitoral/vaginal orgasm controversy, contraception, sexual parapheranalia, even a chapter devoted to selections from the Karma Sutra. In the later chapters, she rolls up her sleeves and lays out detailed ""exercise"" programs for couples afflicted with various sexual dysfunctions: erectile difficulty, premature or retarded ejaculation, frigidity and so on. Dr. Ruth writes like she talks, all abubble, with disarmingly scatty digressions: ""It has been said that the average American knows more about cars than about the clitoris. This is deplorable from my point of view! I would like in my lifetime to raise the level of sexual literacy, especially in this country where I have had such a good time. Especially in Colorado, where the skiing is magnificient!"" Her fans--and they are an ever-growing legion--will undoubtedly gobble this one up.