A riddle is sometimes defined as “a dark saying.” This isn’t only because riddles play with paradox. “The more it’s spied, the less it’s seen,” runs an Elizabethan riddle about the sun. Riddles abolish the names of things; they return us to a world of pure qualities, all of which turn out to be contradictory. But we don’t appreciate their impact until we guess or are told the answer; then, for an instant, a little fracture appears in the stronghold of our nomenclature. Names are shown to hide as much as they reveal. The small art of the riddle involves making some common object momentarily unguessable and briefly wonderful. Take the following example, ascribed to the fourthcentury Latin writer Symphosius:

I bite, when bitten; but because I lack
For teeth, no biter scruples to attack,
And many bite me to be bitten back.

This saying is about nothing darker than an onion. The wit lies in the play on the double sense of “bite.” But the wit also hints at a weirdness in a humble thing. The onion speaks and its voice has a sting of asperity. For a moment our love of onions is called into question: How can we enjoy biting what bites us back? Is the onion the riddle or are we?

The translation above is by the poet Richard Wilbur. Mr. Wilbur has always been attracted to riddles; in several of his collections over the years, riddle-sequences have regularly appeared, often taken from his beloved Symphosius. Each has been an exquisite foray into light verse of the most accomplished sort. But I wonder sometimes if Mr. Wilbur’s fondness for dark sayings doesn’t reveal something unexpected about his own art. The new year just upon us will mark the 60th anniversary of the publication of his first collection, “The Beautiful Changes and Other Poems” (1947). Since that remarkably accomplished debut, Mr. Wilbur has gone on, decade after decade, to produce some of the most beautiful and memorable poetry of our time, all gathered together in “Collected Poems 1943–2004” (Harcourt, 585 pages, $35.).

Though his work has been widely and deservedly praised, it has also seemed at times a bit like Symphosius’s onion. It needs to be bitten into before it bites back. The sustained elegance of Mr. Wilbur’s verse can be misleading. His best poems aren’t the sweet, spherical Vidalias they appear to be, all neatly rippled translucencies, but often betray a sharper pungency. And the surprising, even somewhat disturbing, side of this is that Mr. Wilbur rather revels in that darker taste of things. In fact, he finds it good.

Though Mr. Wilbur’s poetry is consistent in its clarity — he is a poet of sunlit surfaces — many of his poems betray the tug of the earth, of what lies just beneath the surface. In “To His Skeleton,” he resists this tug, admonishing his own skeleton to bide its time: “Noblest of armatures, / The grin which bares my teeth / Is mine as yet, not yours.” But he’s attracted to tubers, corms, potatoes still caked with soil, mushrooms. He takes pleasure in “the delectable names of harsh places,” and in that poem, “Elsewhere,” he states:

That there is beauty bleak and far from ours,
Great reaches where the Lord’s delighting mind,
Though not inhuman, ponders other things.
Of a stone he can say, in riddling accents that evoke Bethlehem:
As casual as cow-dung
Under the crib of God,
I lie where chance would have me,
Up to the ears in sod.

And as if in answer to Symphosius, he has his own rather torrid onion in “A Shallot”:

The full cloves
Of your buttocks, the convex
Curve of your belly, the curved
Cleft of your sex —
Out of this corm
That’s planted in strong thighs
The slender stem and radiant
Flower rise.

This is, of course, a sort of anti-riddle in which the sexy shallot suggests even earthier enigmas. But Mr. Wilbur’s masterpiece in the genre is “Children of Darkness,” from his 1976 collection, “The Mind-Reader.” In this brilliant poem about the lowly mushroom, Mr. Wilbur makes plain that his passion for riddles has a lot to do with his love of the world, that supreme riddle. Here’s how he describes the fungi:

If groves are choirs and sanctuaried fanes,
What have we here?
An elm-bole cocks a bloody ear;
In the oak’s shadow lies a strew of brains.
Wherever, after the deep rains,
The woodlands are morose and reek of punk
These gobbets grow —
Tongue, lobe, hand, hoof or butchered toe
Amassing on the fallen branch half-sunk
In leaf-mold, or the riddled trunk.

The mushrooms look monstrous as spilled brains; they seem grossly out of place in the church-like dimness of the forest. They embody all the ugliness of the world; they’re what the eye discreetly skirts in contemplating nature. For a moment the poet’s tempted to prettify these misshapen things. But his eye — and his nose — are too keen:

Light strikes into a gloom in which are found
Red disc, grey mist,
Gold-auburn firfoot, amethyst,
Food for the eye whose pleasant stinks abound,
And dead men’s fingers break the ground.

In “Potato,”an early poem, Mr. Wilbur turned his remarkable nose on that tuber and noted,”Cut open raw, it looses a cool clean stench”; he found its smell like “a strangely refreshing tomb.” His mushrooms aren’t beautiful either, for all their jeweled glints. What they have surpasses mere beauty; they have the irresistible pungency of the real. He ends the poem with the three words: “They are good.” What startles here (as elsewhere in his work) is not that he confronts the “children of darkness,” but that he finds them good. A true son of Whitman, Mr. Wilbur has an unshakable sense of the ultimate goodness of the world. That’s not just an uncommon insight but a brave one, especially today.

The great Austrian poet Hugo von Hofmannsthal once wrote, “Depth must be hidden. Where? On the surface.” For 60 years Mr. Wilbur has been hiding depth on the surface. And isn’t that precisely what the best riddles do?

eormsby@nysun.com