Twenty more sensitive, thought-provoking nature essays by the author of The Run, The Great Beach and The Undiscovered Country. It's hard to write about ""the mysterious language of the earth,"" and even harder to make us hear it, but Hay does both with a grace and occasional brilliance that make his quiet essays a pleasure to read. Whether he is discussing loons, icebergs, butterflies, hickory trees or the rare yellow-nosed vole of Maine, his mixture of personal anecdote, scientific fact and philosophical speculation gently draws the mind into new ways of thinking about the natural world. We are asked to consider what it really feels like to be a pelican, to look at ourselves for a moment from the point of view of a loon, to listen to ""the undercurrents of the soil,"" to imagine New England's trees as migrants from other parts of the country--and all with a deeply felt sincerity and calm enthusiasm that are both infectious and believable. If the prose does not always attain the poetic perfection for which it understandably strives, it gets close enough to show us a thing or two: for example, the tropical rain forest as ""a great self-perpetuating wheel of light and growth,"" which not only captures the complex beauties of that particular ecosystem but manages to conjure up, with a concrete image, the kind of mystical, aesthetic vision of things with which this author's best pages are permeated. ""There is a point,"" he writes in his preface, ""at which science leaves off, and you have to trust to the lasting wilderness receptor in yourself."" It is at that point, and with that kind of trust, that Hay writes best. Where he occasionally slips--as in his first essay on Los Alamos--is just where he comes back from that point and, confusing the aesthetic and the ethical, starts to moralize. But all that is forgiven against the serious strength of his vision. A worthy contribution to the science of ecological aesthetics.