Robert Frost thought that “poetry is what is lost in translation.” This seems harsh. Pope’s Homer, Fitzgerald’s “Rubáiyát,” Arthur Waley’s or Ezra Pound’s versions from Chinese and Japanese — and many other examples — prove Frost wrong. Yet I know what he meant. All I have to do is flip through “Feuilles d’herbe,” the French translation of “Leaves of Grass,” to recognize that something essential has been lost. The French title feels wrong. Our grassblades are robust, tough, and scrubby and have nothing in common with the vaguely perfumed aura of “feuilles d’herbe.” According to the Italian proverb, the translator is a traducer, but could it be that languages betray one another? Frost claimed that poetry, to be appreciated, requires “the imagining ear.” He meant that we apprehend “the sound of sense,” always close to actual speech, as it blends, or contends, with the metered patterns of poetic form; a delicate whipsaw effect, discernible only to the native ear. And this, of course, must be lost in another language.

The poor translator can’t win. A correct but literal translation will be dismissed as unpoetic while a poetic version will be trounced as inaccurate. And for some reason I don’t understand, translations from Romance languages, especially French, Spanish and Italian, appear especially vulnerable to this fatal double bind. I suspect it’s because in those languages, the vowels predominate, displaying the subtlest of shadings, and this is hard to duplicate in thuddingly-stressed, consonant-heavy English. Still, some translators — John Hollander, Anthony Hecht, Richard Wilbur among Americans, Tony Harrison and Derek Mahon among the British — do succeed, often to dazzling effect, perhaps because all are superb poets in their own right.

The distinguished translator Edith Grossman, justly praised for her wonderful versions of Gabriel García Márquez and Álvaro Mutis, among others, as well as her splendid recent translation of “Don Quixote,” has now taken on this thankless challenge.In “The Golden Age: Poems of the Spanish Renaissance” (Norton, 201 pages, $26.95), Ms. Grossman gives us verse renderings of eight classic Spanish poets, with the Spanish texts on facing pages. She stretches the temporal and spatial boundaries of the “Siglo de Oro” to include the sombre 15th-century master Jorge Manrique as well as the late 17th-century Mexican metaphysical poet Sor Juana de la Cruz; the others — Garcilaso de la Vega, Luis de León, St.John of the Cross, Luis de Góngora, Lope de Vega, and Francisco de Quevedo — form a baroque constellation of lyrical genius unusual at any place or time.

In one of his sonnets, not included here, Quevedo celebrates the solace his books give him; they are “few but erudite,” he says, and yet through them, he holds “a conversation with the deceased.” In a following line, which should be engraved on the façades of libraries, he states, “I listen to the dead with my eyes.” When we read, we listen with our eyes; we transform something seen into something heard, if heard inaudibly. But when we translate, we must startle our ears, and those of our readers, awake. The eight poets in Ms. Grossman’s selection are all intensely sonorous; their poems were written not only for the “imagining ear,” but for the ear of flesh (many of them have been beautifully set to music). Sadly, little of this vivid melody survives in Ms. Grossman’s versions.

Part of this has to do with her tendency to pad; where Spanish employs one sleek word, she inserts two or three. Here is how she renders the first stanza of a sonnet by de la Vega (1503–36), who brought the Petrarchan mode into Spanish:

Brave Leander, dauntless, crossing the sea,
On fire with the blazing flames of love,
When winds blew strong and waters rose and swirled
With frenzied rage and driving, crashing swells.

De la Vega simply calls Leander “brave” (“animoso”) but Ms. Grossman feels impelled to tack on “dauntless” as well. He speaks of the “amorous fire” but this becomes “on fire with the blazing flames of love,” both padded and hackneyed. In the Spanish the water merely “rages”with a “fierce impetus” while the translated line is waterlogged with superfluous verbs and gratuitous adjectives. The original, for all its tropes, has naked force; the translation is at once blustering and inert.

Spanish with a smaller vocabulary than English makes its words work harder. But there is something almost desperate in the way Ms. Grossman heaps up redundancies. In trying to render the “Dark Night” of St. John of the Cross — admittedly an untranslatable poem — she resorts to “on a dark night, deep and black,” when the Spanish says only “on a dark night” (“en una noche oscura”). And the enigmatic and lovely “O happy chance!” (“¡oh dichosa ventura!”) becomes “what great good fortune was mine! “In laboring to match the power of the original, Ms. Grossman lessens it; this is less translation than a form of verbal upholstering.

She’s at her best when she turns to Quevedo, arguably the greatest of all Spanish poets. Her versions of the “Metaphysical Poems” catch something of his elegant ferocity. In “Fortune has gnawed at my allotted time,” Ms. Grossman replicates his mordant assonance. And she echoes his conclusion well:

Yesterday’s gone, tomorrow’s not yet come,
Today’s in headlong flight and will not stop;
I am a weary was, will be, and is.
In my today, tomorrow, yesterday
I join swaddling and shroud, and have become
Present successions of the same dead man.

She succeeds too in her translation of Manrique’s “Stanzas on the Death of His Father.” This eulogy possesses a double timbre; its words are profoundly mournful but its cadences have a surging jubilance. It takes its form and its momentum from a famous image at the outset: “Our lives are the rivers / that empty into the sea / that is our dying.” Death is not an end but a continuum where we all must flow. Though Ms. Grossman conveys the grave stanzas expertly, the best way to hear this incomparable poem, especially for the first time, is to listen to the performance by the great Spanish singer Paco Ibáñez who set it unforgettably to music; at moments you almost feel that Death himself is strumming the guitar strings.

You’d never guess from Ms. Grossman’s selection that most of these poets were not only death-obsessed in the finest Spanish tradition but also boisterous, swashbuckling, given to outrageous high jinks, and quite exuberantly obscene. Quevedo and Góngora loathed each other, and traded insults of such lewdness as to be unprintable here. This is, by contrast, a well-mannered anthology. Only when mortality whispers from the sidelines do the translations quicken and alert “the imagining ear.” But then for all poets, and not only Spanish ones, death has always served as a “salsa picante,” a metaphysical hot sauce for the soul.