The achievement of the strenuously lionized British realist painter Lucian Freud has not so much been to break new ground as to dig incessantly deeper into the old. By doing so he has intensified our understanding of figurative painting’s familiar landmarks to the point of discomfort. Among these landmarks are the figure and its interior life, the artist-model relationship, the nude isolated on the private stage that is the studio, the arduous process of seeing and painting reality and, finally, the place of the viewer in it all. In Mr. Freud’s work they all become macabre, even scary. Mr. Freud, who turned 85 last week, has managed this in no small measure by painting only people he knows and cares about, while equating flesh with oil paint. His strenuously worked surfaces portray bodies and faces in ways that convey a punishing sense of life lived — of too, too solid flesh weighed down by experience, indulgence and cowardice. His canvases never let us lose sight of the effort required to get the painting painted. The rough, slathered expanses offer unstinting views of flesh, thick and folded, or stretched thin over all-too-visible bones, of faces sad or pensive or blank. The portrayals are physical but not sensuous, harsh yet intensely engaged — the painterly equivalent of tough love. Again and again they grant the model enormous respect, but no place to hide. It would be simplifying things to say that the density, plasticity and color of oil paint provide Mr. Freud a place to hide. Yet this impression may come to mind in “Lucian Freud: The Painter’s Etchings,” a riveting exhibition at the Museum of Modern Art. Moving through its galleries, you may conclude that tough as Mr. Freud’s paintings are, his etchings are somehow even starker, more raw and brutal. They bring the violence of his rendering style closer to the surface. Compared with the loamy explorations of Mr. Freud’s paintings, the etchings might almost be X-rays. The best show us sides of the image, like scaffoldings that have been partly draped with nets — often hallucinatory patches of lines, gouges, hatching and crosshatching. The frenetic marks lead lives of their own while somehow also coalescing to imply flesh, features and expression, in varying degrees. Sometimes this happens with breathtaking minimalism, as it does in Mr. Freud’s images of a nude blond woman he depicted several times between 1985 and 1990 in both paintings and etchings. In the etchings all signs of furniture have been left out, and the body floats in space. Sometimes the coalescence is a thoroughly considered architecture of lines, as it is in the great “Lord Goodman in His Yellow Pyjamas,” from 1987, in which an astoundingly homely face looms like a small, heaving mountain. Both images might almost be constructed from fine wire: we remain completely aware of the thinness of the image and the white paper just behind it.This show of nearly 100 works, organized by Starr Figura, the museum’s assistant curator of prints and illustrated books, is not the first large survey of Mr. Freud’s etchings in the United States. This one, though, is about one-fourth paintings, and the mingling is a good ratio. The 66 etchings here — only 16 short of the artist’s total output — are pitted against 21 paintings. The paintings offer respite from the etchings without forming a permanent means of escape. The wildness of line that etching offers is hinted at early in the exhibition in “A Couple” (1982), a tiny work of a cackling pair, seemingly in a photo booth. It becomes overt on the next wall, where three etchings of Mr. Freud’s mother from 1982 are grouped with two paintings of her from the early 1970s, when the artist’s thickly painted realism was just beginning to gel. Contrasting noticeably with the relative composure and self-containment of the painted portraits, the etched ones are a tumult of scowls and unruly hair. The most extreme describes the subject’s face as a series of ravines and terraces culminating in a rutted upper lip that seems almost cleft. Mr. Freud’s 1982 etchings were the first he had made in 24 years. The show begins with a few etchings from 1947 and 1948, early works by the artist, who was born in Berlin in 1922 and whose family emigrated to London in 1932 because of the Nazis’ rise. His sealed-off, exquisitely controlled, linear manner implied a need for order and a preference for emotional tension satisfied by small, oddly angled, tightly framed images that worked better in paintings than in prints. But incipient signs of his obsession with texture and strangeness can be found in “Man With a Thistle (Self-Portrait),” a painting from 1946 in which the artist’s steely blue eyes haughtily size up his own reflection. The intarsia-like stiffness of his thick brown hair foretells the roiling surfaces of Mr. Freud’s mature work. It took his full attention and more than a decade to bring his painting even close to a genuinely active roil. It helped that the painter Francis Bacon, a close friend, persuaded him to trade his small, stiff sable brushes for ones of bristle that were softer, less controllable and better carriers of paint. By the late 1950s Mr. Freud was rendering figures in juicy helter-skelters of strokes reminiscent of the work of Frank Auerbach. He then gradually bore in on paint and sitter alike, recapturing some of the detail of the earlier work while making the surfaces more tormented. Mr. Freud’s 1982 return to etching came casually, when he agreed to make prints to be inserted in 100 copies of Lawrence Gowing’s monograph on his work ( to help meet the costs of publication). He picked up where he had left off, with close-ups of women’s faces, but with a new, more physical grasp of line. In “Head on a Pillow” lines slalom across the paper, defining pillow, hair and shirt, but bunch around the features, casting dark shadows and defining the tip of the nose as a stack of textured discs. By 1987, as the portrait of Lord Goodman attests, he was hitting his stride. You can retrace his progress by following the several portraits of his daughter Bella Freud, starting with her first appearance here, in a small, beautiful painting from 1981. A series of etchings culminate in a hard-won 1987 portrait where the topographical grandeur of her face yields none of its delicately thoughtful expression. In many ways Mr. Freud’s etchings gained power from the cruelty of light when rendered in the black and white of etching. You can imagine this fact dawning on him while depicting the obese, dozing figure in “Woman With an Arm Tattoo,” another print from 1987. Here the eye speeds past the woman’s immense blemished bicep and the halter top that resembles a plowed field to struggle with her nose, a crumpled form not unlike a squashed soda can. This show has its dead spots, including three states of a large seated portrait of Bella from 1995 that seem to be little more than empty, technical grandstanding. Manipulations of light reach an extreme in the 1990s with portraits like “Kai,” “David Dawson” and “Head of Ali,” whose male subjects might almost be wearing war paint. Three portraits of men made since 2005 suggest that something both softer and grander is creeping into Mr. Freud’s etchings. Along with two searing self-portraits, they bring the onslaught of his printed art to a suitable close. This may be the first exhibition in New York that really gives Mr. Freud’s etchings their due. Previously they have tended to be overwhelmed by the sheer heft of the paintings. Given a 3-to-1 advantage, the etchings prove that Mr. Freud does perfectly well, maybe even better, traveling light.