Jorge Guillen has lived in this country for many years, but when the poet - acclaimed as one of the greatest in our time by a whole chorus of citics - won the Cervantes Prize last year, the most common reaction in his adopted country was one of mild puzzlement. Guillen is an Andalusian and writes in Spanish; his reputation flourishes chiefly overseas and among a small group of specialist and enthusiasts here. That situation is about to change; selections from his magnum opus have edition, in a bilingual paperback edition, with translations by such fellow-poets as Ben Belitt, W.S. Merwin, Richard Wilbur and James Wright: Cantico: A Selection edited by Norman Thomas di Giovanni (Atlantic/Little, Brown, $6.95). This volume has absorbed the poet's creative energies through most of his career, growing through most of his career, growing through successive editions into a compilation of over 300 poems, one of the most imposing collections of our time. Fifty of the most significant and characteristics works from Cantico have been selected by Guillen, and the resulting volume gives, in two languages, a well-rounded view of a writer who is certainly a living classic, notable equally for the depth and breadth of his vision, his care for formal values in writing and the pure gusto with which he affirms the value of living.