Poetry from two grandmasters of nuance; Vicente Aleixandre lights the way; A Longing for the Light: Selected Poems of Vicente Aleixandre. Edited by Lewis Hyde. New York: Harper & Row $12.95.

The poet," according to Vicente Aleixandre, who won the Nobel Prize for literature in 1977, "is essentially a prophet. . . . His job is to illumine, to aim light."

Poetry, for Aleixandre, is "a longing for the light."

Lewis Hyde uses that existential phrase as the title for Aleixandre's first volume of selected poems in English. The 15 translators include editor Hyde.

Why, we might ask, since Aleixandre is 81, did it take so long for his work to appear in English?The answer: This poet, prophet or not, was neither controversial enough nor political enough to interest a commercial publisher before he won the Nobel.

Some of his early poetry might tax a reader with its mysticism and disjointed style. But Aleixandre's poetry loses much of the disconnectedness in later years, and begins to address people directly -- real people, and people of the past. Gone are the terrible black mountains at the bottom of the sea. Instead, we find the sunlit streets and classrooms of his childhood. Suddenly -- light.

In "The Old Man Is Like Moses" Aleixandre assures us: . . . every man can be like that and deliver the word and lift his arms and feel how the light sweeps the old road dust from his face . . . his mouth full of light.

More and more he sees the world "exhaling a vegetable joy." "On the Way To School," a poem about bicycling, ends with the boy-he- was folding his wings at the school door.

There also are Dickinson- like flashes: "Kill me sun, with your impartial blade." Wordworthian messages: "inside the small boy is the man he will become." And fire everywhere: "I am the horse who sets fire to his mane."

Pedro Salinas said, "Vicente, delicate and apart, has discovered that love plus desperation equals poetry, deep, strangely moving poetry." To which we add, "poetry filled with light."