In SHIKASTA, the first volume of Doris Lessing's "Canopus in Argos: Archives" series, the author announced that she had chosen to use the conventions of "space fiction" because they offered her freedom. Her new works, she said, would be set in a realm where "the petty fates of planets, let alone individuals, are only aspects of cosmic evolution expressed in the rivalries and interactions of great galactic empires."

The problems of making this vision comprehensible, not to mention interesting, to the petty human reader are well illustrated in Shikasta and the second volume of the series, The Marriages Between Zones Three, Four, and Five.

The freedom offered by science fiction and fantasy -- the freedom to create, to dream, to envision new worlds through which to explore this world -- does not imply a freedom from the traditional values of fiction, or, for that matter, from common sense and the laws of probability. In Shikasta, Lessing arbitrarily misused sf conventions to set up a visionary, but abstract philosophical discussion. In Marriages, which she describes as both "a fable, a myth" and as "more realistic," she succeeds better in rooting her ideas about men and women, civilization and social change, art and vision, firmly in an interesting plot and plausible characters.

Marriages is, indeed, both "realistic" and mythic. In fact, one of its concerns is the way that ordinary life becomes transformed into fable and popular art. Lessing's narrators are the Chorniclers and song-makers of Zone Three, an imaginary (and alas, shadowy) realm whose queen, Al.Ith, has just been ordered to travel to Zone Four, there to marry its king, Ben Alta.

The king and queen are individuals, puzzled and disturbed by these orders from their mysterious over-lords, the Providers. Unfortunately, for the Providers and for Lessing, they are also abstractions, representatives of their realms. In one sense, this is the true stuff of myth; the lands are ailing, and the marriage of these sympbolic figures will bring healing and beneficial changes to both zones. Yet this is not the Middle Ages; symbol and reality are not one, for us. Lessing is not writing a brief fable, but a modern novel. Her book is weakest when she simply uses Al.Ith to embody the ideals of her zone, and perhaps of Woman: she is sensitive, idealistic, sexually liberated, cultured and so on; and when she uses Ben Ata to represent the defects of his zone, and perhaps of Man: he is insensitive, militaristic, sexually unliberated (he literally does not know how to perform a sexual act which is not a rape) and so on.

"The nature of Zone Four -- it was conflict and battle and warring. In everything. A tension and a fighting in its very substance: so that every feeling, every thought held in it its own opposite." Such generalizations occur far too often; the reader is told too much, not shown enough.

The book is strongest when its central characters are allowed to come together as themselves, not as partners in "an exemplary marriage," but as Al.Ith, a woman who weeps, learns jealousy and dependence, and ultimately, in exile from both realms, seeks the splendor of mystic Zone Two; and as Ben Ata, a bumbling but rather likeable person who learns that men and women can be friends.

The title is something of a misnomer. The book concentrates on the nuances of the realtionship between Al.Ith and Ben Ata, as they meet, part and engage in a good deal of introspection, much of it with Broader Implications For Our Time. Near the book's end, after Al.Ith has been ordered to leave her husband and child for the last time, Ben Ata is ordered to "marry" the barbarian princess of Zone Five, so that the social and cultural changes caused by the interaction between the zones will continue.

In the opening paragraphs, Lessing effectively captures both the feel of an oral culture, transforming actions into legend, and the specific tones of a human voice. The narrator introduces the idea of the marriage, which has already become the subject of rumor, speculation and song.

"What was being said and sung in the camps and barracks of Zone Four we do not choose to record. It is not that we are mealy-mouthed. Rather that every chronicle has its appropraite tone.

"I am saying that each despised the other? No, we are not permitted actively to criticize the dispensations of the Providers, but let us say that we in Zone Three did not forget -- as the doggerel chanted during those days insistied: Three comes before Four, Our ways are peace and plenty. Their ways -- war!"

The book is successful as long as it maintains this delicate balance of fable and human reality. Unfortunately Lessing isn't content simply to let her chroniclers ask the necessary philosophical questions: "What, in this context, was a wedding? What, even, a marriage?" Instead, she manipulates Al.Ith, Ben Ata and the minor characters to illustrate an essay.

Lessing does provide wonderful human scenes. Al.Ith's growing friendship for Dabeeb, wife of Ben Ata's chief general, and her introduction to the underground women's culture of patriarchal, repressive Zone Four are vivid and moving. In secret ceremonies, the women support each other's heads, looking up towards the mountains of Al.Ith's country. Then they don the heavy metal helmets that anyone caught "cloud-gathering," gazing upward to glory instead of down to the earth, must wear, and flee home.

Those helmets, though: aren't they a touch too symbolic? The Zones: where are they? Are they real places, or a collection of qualities? (In Shikasta, Zone Six is where the souls of the dead go to await rebirth." The Zones are divided by an "invisible barrier," a sudden change in the density of the air." One can move between them only by wearing a protective "shield". Oh really? Lessing uses such "space fiction" conventions arbitrarily, merely as devices to "explain" why there has been little previous contact between Zones. She forgets that, if you are to build a world out of words, it must be solid, consistent and real.

Marriages, then, is least successful when its outer framework is rickety, too obviously carpentered up merely to support a moral and philosophical discussion. It is most successful when its inner heart, the realtionship between Al.Ith and Ben Ata, makes us feel and understand Lessing's ideas in human terms.