Eskimo sculpture from an icy world; Lords of the Stone, by Alistair Macduff. North Vancouver, British Columbia: Whitecap Books (Suite One, 431 Mountain Highway, V7J 2L1 CANADA).148 pp. $45.

With the gift of understatement, Eskimo sculptors have been forming wonderfully fluid statements of their icy world for centuries. Whales, seals, walruses, sea birds, human and legendary figures, and images of the hunt are shaped with an honesty born of primitiveness, yet with the restraint and refinement of fine art. The Inuit work in soapstone, whalebone, and ivory hints at the shapers' legends and livelihoods, their imagination and humor.

Arctic sculpture is all the more intriguing when one considers it against a backdrop of 5,000 years of Eskimo life under conditions of cold and isolation. As a subject, it calls for intuitive compassion as well as artistic knowledge.

In Alistair Macduff the Inuit artists have such a spokesman. As Director of Victoria's Gallery of the Arctic and consultant to Canada's Museum of Man, he has traveled some 250,000 miles in the northland, sometimes by snowmobile and dogsled, has lectured widely, and has selected Inuit sculpture for display.

These experiences and especially his own excitement about the Eskimo work have culminated in this dramatic volume, ''Lords of the Stone.''

In a highly personal style, Macduff shares his awe of discovery of this new-old art. His text is sprinkled with digressions into Eskimo life, accounts of his art-hunting expeditions, and Eskimo legends which are reflected in the sculpture. The text is accompanied by 84 color plates by photographer George Galpin, showing works from eight arctic communities.

Macduff succeeds in demonstrating the classical, lyrical quality so often apparent in a delicate caribou or sea bird. He shows how the artist conveys intense emotion, even while working the stone minimally, by the imploring gesture of a tiny hand or the warmth of a mother's and child's faces enveloped in the hood of a single parka.

Under his pen the sculptures tell the modern world of an elemental life of purity - naive, self-contained, and wonderfully expressive.