The Janus-headed career of Philip Guston continues to baffle and to engender both supporters and detractors. And people tend to prefer one head to the other. Standing in the first room of the Morgan Library & Museum’s beautiful though uneven show of Guston’s works on paper, Isabelle Dervaux, who organized the exhibition at the Morgan (its only American venue), asked me which Guston I preferred. When I told her I liked 1950s Guston much more than late Guston, she jokingly suggested that I skip the second half of the chronological show. But that would have been a mistake because, as this exhibition demonstrates, Guston was less schizophrenic than he has been made out to be.

Guston (1913-80) was born in Canada to Russian immigrants. He grew up in Los Angeles. As a child he copied “Krazy Kat” and “Mutt and Jeff” comic strips. In 1928, along with fellow student Jackson Pollock, he was expelled from Manual Arts High School for distributing satirical propaganda that lampooned the school’s English and athletic departments. He took odd jobs, studied briefly at the Otis Art Institute, tried his hand at movie acting, made murals for the WPA, and became increasingly interested in politics, creating, among other controversial works, the huge mural “The Struggle Against Terrorism” with Diego Rivera in Mexico City. In 1936, he belatedly followed Pollock to New York, where — befriending artists and poets, teaching, writing, lecturing, and exhibiting — he became a central and influential figure of the New York School.

And yet, Guston reached the pinnacle of his career in both talent and reputation with a relatively small body of work — his signature pure abstractions of the early 1950s. During that period, Guston created some of the most lyrical yet architectonic paintings and drawings of any Abstract Expressionist. Beautifully scumbled, roughened, and dense yet also airy, and often in a fleshy, summery palette of pinks, reds, blacks, and grays, these abstract paintings, in which ribbons and rectangles appear to fluctuate within a gathering field, have a formidable frontal presence and call to mind skin, landscape, fluid, and cosmos. They are delicate and restless, meaty and graceful. They suggest the “Pier and Ocean” period of Mondrian, the “Water Lilies” of Monet, and the delicately interwoven patterns of Vuillard. They are among the most elegant and light-of-touch — in some ways, perhaps, the most “School of Paris” — paintings of the New York School.

But Guston was pulled to the things and to the “thingness” of the world, especially its detritus. His friend Philip Roth recalled, “We discovered we both liked American junk.” During the late ’50s, Guston began to stray back to figuration — which is where he began. In 1970, when he exhibited a new, nearly career-breaking body of work at Marlborough Gallery that included large lone shoes, cigarettes, lightbulbs, and hooded Klansmen, his work was derided as cartoonish, crude, blunt, and buffoonish. He had turned his back on abstraction completely. The consensus was also that he had betrayed the New York School.

The Morgan’s show of 100 works is the first major survey of Guston’s drawings in 20 years. It begins oddly and tidily in 1946 (when Guston was 33), which is a rather late start for a retrospective. It includes none of his student work, sketchbooks, mural studies, or drawings from Renaissance masters. We are given no sense of early or formative Guston. Instead, the exhibition throws us deep into midstream, just as the artist is warming up to a crescendo. The show flowers early and briefly (the second wall is the most elegant), then trails off in numerous directions. Still, it presents the full spectrum of Guston’s drawings between the late ’40s and the late ’70s; and, because the works on paper were extremely important and pivotal to his movements as a painter (for two years beginning in 1966, for instance, Guston stopped painting and produced only drawings), the show provides an intimate framework of the inner workings of the artist.

Like any painter, Guston did not so much evolve as explore different sides of himself — pushing in one direction and then another. What is clear is that Guston was a metaphorical painter, of which there are basically two types. The first includes an artist such as Paul Klee, for whom each picture is a singular and exacting exploration of a chosen poetic theme (the conflation, for example, of the structure of a stained glass window with that of a plant). Like most of the Abstract Expressionists, Guston falls into the second group. His abstractions of the ’50s are more general explorations — a kind of plowing forth through a theme — in which an overarching metaphor or approach to life is explored in series.

In the ’50s abstractions, Guston flays the world, bruises, nurses, and caresses it, builds it up, and breaks it down. His abstract pictures suggest stone walls, skeletal structures, tangled webs, bunches of fruit, ruined temples. And their coloration — the pinks, golds, and reds — along with their insistent start-and-stop motion make them living, breathing organisms.

This period of abstractions at the Morgan is the most fluidly calligraphic and satisfying. The spare “Drawing” (1951), in which shapes recall lighting, a primitive stone tool, a vaginal form, and a fruit with stem, has the geometric precision of an Ellsworth Kelly. Another ink-on-paper work is as dense as a thicket. Others suggest the migration or evolution of point to line to plane. In “Drawing No. 2 (Ischia)” (1949), Guston, through the depiction of floating tiny cobblestones, windows, and corridors, creates a twinkling abstract city — a distant fairy-tale island lodged in the sky of one’s memory.

Sometime after 1955, however, Guston begins to name things in his drawings. He also gives up abstract space and begins to place those things on representational, or figurative, stages, as if they are performers in dramas. His forms, now grounded, both literally and figuratively, begin to narrow metaphorically. The gouaches “Dark Form II” and “Accord II” (both 1963), in which black masses occupy gray-violet fields, are lush and foreboding. But they do not have the staying power or freedom of association found in the earlier abstractions.

In the work from the 1960s, Guston pares down forms even more. He arrives at gorgeous and suggestive linear distillations in black ink on white grounds — a cross, rectangle, scribble, dash, figure, or oval. Many of these drawings recall pictographs or signs. At their best, they are both bare beginnings and final solutions — the alpha and omega of pictorial form. But, despite their strength as images, they can also feel stripped too close to the bone.

By the late 1960s, when Guston is making single images of lone books, Klansmen, clocks, and shoes, the work, though elegant, has difficulty eschewing an overarching clownish and cartoonish clumsiness. In these late works, Guston can still draw; and he remains a great colorist, but his subjects begin to close down into emblems or narrow narratives. In “Untitled (Cherries)” (1980), a large pile of bloodred cherries, with spiky stems, suggests a crown of thorns or severed heads piled like cordwood. Other configurations of piled objects, shoes, junk, and earth bring to mind futuristic dumps and Kafkaesque machines. These later narrative drawings are well-executed, but feel more like magnifications of limited ideas than full explorations of poetic themes.

Guston firmly believed that he was a narrative artist at heart. He wanted “to tell stories.” And artists, above all else, have to remain true to themselves. They have to follow their gut instincts. Guston’s art remains inventive and engaging to the end. The fact remains, however, that, despite Guston’s convictions as a storyteller, his earlier pure abstract pictures are much more inventive and engaging as stories than his later stories are as pictures.

Tomorrow through August 31 (225 Madison Ave., between 36th and 37th streets, 212-685-0008).