Larry Niven fans should be aware that this book features work by nine authors, including Niven himself. He contributes a one-page introduction, "The Magic Goes Away" itself, "Not Long Before The End", and "The Lion In His Attic". There is also "Talisman", a collaboration between Niven and Dian Girard. Of the 358 pages, Niven alone contributes 125 (35 percent); if you include "The Talisman", this rises to 160 pages (45 percent).
For my money, the first two stories stand head and shoulders above the rest (with one exception). "The Magic Goes Away" is more of a novella than a novel, running just 90 pages, but its striking originality makes it linger in your mind. The basic thesis is that magic used to exist, long ago, but that it depended on a natural resource called mana which the magicians of the time depleted, just as we are using up fossil fuels. This simple change to our understanding of the universe allows Niven to construct an elaborate "alternative history" while technically keeping one foot in the domain of science fiction. For instance, we read how Atlantis was preserved by spells woven by its priest-kings, which gave way when Greek invaders killed the priests. The plot concerns how a group of sorcerers join together, in spite of powerful enmity and distrust, to find some new source of mana - without which their longevity spells will lapse, dooming them to immediate death (as they are all hundreds of years old). Their quest involves crossing the ocean on cloud-tops, and planning to steal the last surviving god from its place of rest.
"Not Long Before The End" is a "prequel" to "The Magic Goes Away", giving a full account of a critical incident merely referred to in the earlier story. Although only ten pages long, it has the mixture of excitement and intellectual adventure that characterize Niven's best work. "The Lion In His Attic" is set in a drowned castle, years after the flooding of Atlantis. Two strangers arrive, ostensibly on honeymoon, but actually seeking a magic emerald. They make the mistake of underestimating the "lion" of the title - a highly qualified guardian whose nature they could hardly have expected. "The Talisman", co-authored with Dian Girard, though perhaps less ambitious and more subtle, paints an equally fascinating picture of magicians, thieves, kings, and soldiers.
The other stories are a mixed bunch, but none of them is less than readable. Fred Saberhagen contributes "Earthshade", an elegant miniature that neatly imports the Greek pantheon into Niven's "magic" universe. Less exalted, earthier and more complicated is Dean Ing's "Manaspill", which deals with how a court magician might use a windfall of mana to further his ambitions. I admit to being rather baffled by Steven Barnes' "...But Fear Itself", with its mystical vision of an enslaved tribe that uses the magical power of its children to wreak a terrible revenge on their oppressors. Poul Anderson is a writer whose books I have alway enjoyed, and "Strength", which he co-wrote with Mildred Downey Broxon, is the sort of post-apocalyptic adventure in which he excels. Shalindra, the widow of a sorcerer, rescues the hunter and practical man Brandek after a shipwreck, and the story develops the tension between her yearning after the old ways of magic and his determination to make a fresh start using simple technology.
Then we come to "The Shadow Of Wings" by Bob Shaw, another fine example of the "magician conspiring against the king" sub-genre. Even King Marcurades, who comes across as a blend of Alexander the Great and Edison, is a pawn in the hands of those who control mana - as long as they do control it, that is. And then, just as the book is nearly finished, we come to the best surprise of all: a fine piece of work by no less an author than Roger Zelazny! The protagonist of "Mana From Heaven" is a sorcerer at the height of his powers, but he is threatened by unknown assailants for reasons he cannot guess. No one has ever been better at telling this kind of story, and Zelazny does not disappoint.
I began by being aggrieved that Niven had written less than half of this book, but the more I read the more I liked it. The other authors (apart from Zelazny) may not quite rise to the levels of which Niven is capable, but they introduce a fascinating variety of points of view and emotional climates. All in all, strongly recommended!