SAN FRANCISCO — There’s nothing nicer than going into a major museum show like Wayne Thiebaud: Art Comes from Art at the Legion of Honor filled with wariness around its (obvious?) premise and leaving not just convinced, but charmed. To be clear, I was already a Thiebaud fan. Colorful and fun, while deeply earnest about the enterprise of art making, his paintings seem to take serious delight in his subjects and sources, whether exquisite cakes or a sprawling California Delta landscape. And though his work has often been understood in the context of his native California — those dramatic rural and urban landscapes, that bright palette, all those saccharine goodies — isn’t the idea that it’s also indebted to earlier art a given? Why should it be different for Thiebaud than any other painter? Turns out, it’s a difference of degree, and Thiebaud cranked his art amp to 11.The show opens with a single work, “Betty Jean Thiebaud and Book” (1965–69), wherein the artist’s wife is depicted in a plunging black V-neck, a pale headband in her dark hair connecting her to the pale background. She stares ahead, her hand along one side of her face, her elbow resting on a white surface, ignoring the open art book in front of her that contains black and white reproductions on facing pages. The cascade of art historical impressions is immense. Installation view of Wayne Thiebaud: Art Comes from Art at the Legion of Honor, San Francisco. Center: “Betty Jean Thiebaud and Book” (1965–69) (photo Bridget Quinn/Hyperallergic)Curator Timothy Anglin Burgard describes the portrait of Betty Jean as Thiebaud’s “Mona Lisa,” and you can instantly see why, as their enigmatic expressions are similarly mysterious. There’s also the book, in which the reproductions can be made out as drawings by Georges Seurat and Edgar Degas, artists whose draftsmanship Thiebaud admired. And the black and gray arrangement to portray a woman in an American artist’s life gives off a whiff of James McNeill Whistler. In a wall text near the painting, alongside the usual didactic, are small reproductions of works by Albrecht Dürer, Jean-Auguste-Dominique Ingres, Degas, and Pablo Picasso that might have consciously or unconsciously inspired Betty Jean’s hand-to-side-of-head pose.In a film that accompanies the exhibition, Burgard explains that Thiebaud appropriates in three ways: overt theft, as an homage to the earlier art and artist; covert theft, in which he conceals his source imagery; and intuitive transformation, where he has digested the source and it is in him. A lot of the enjoyment of moving through the exhibition is spotting the Easter eggs of earlier art, whether overt, covert, or something even more subtle.Wayne Thiebaud “35 Cent Masterworks” (1970–72), oil on canvas; Wayne Thiebaud Foundation (© Wayne Thiebaud Foundation / Licensed by VAGA at Artists Rights Society (ARS), NY)Sometimes the connection is obvious, as in “Standing Man” (1964), whose White businessman in a standard grayish suit stands, arms hanging by his sides, against a pale backdrop and ground. His pose and resigned expression immediately call to mind Jean-Antoine Watteau’s famous “Pierrot” (1718–19), the white-clad commedia dell’arte everyman and clown. Yet the wall label also points out a less obvious, but clear, relationship to the black and white photographs of everyday Germans by August Sander.Such connections as these are fun to find and see, while others initially struck me as unlikely, as in one of Thiebaud’s early figurative works, “Nude” (1963), paired with a reproduction of Edvard Munch’s “Puberty” (1894). Both are female nudes, but while Munch’s is not much more than a girl, wide-eyed, arms crossed over her hunched body, a little haunted, Thiebaud’s woman is voluptuous, seen head on, her hooded eyes looking out impassively. It’s an entirely different vibe — but then I consider the cast shadow in both works, the dark hair and the white surface on which both figures are posed and, yeah, it feels apt to compare them.Wayne Thiebaud “Woman in Tub” (1965), oil on canvas (photo Bridget Quinn/Hyperallergic)The exhibition includes many other comparisons that are somehow both obvious and not. For “Woman in Tub” (1965), I immediately thought of Jacques-Louis David’s “Death of Marat” (1793), but then asked myself if any painting of a person in a tub might have the same resonance when your brain is saturated with art historical imagery. As an artist and influential teacher of art, Thiebaud was more immersed in such images than most, from many eras and cultures, including the art of his contemporaries and immediate predecessors in the United States. His “Road Through” (1983), for example, is an amusing riff on Barnett Newman’s abstract “zip” paintings, but here Newman’s spiritual-tinged other world becomes a vertiginous highway slicing through nature. Thiebaud’s insistent focus on this world might be one reason why he has often been mischaracterized as a Pop artist. But even his cake paintings — probably his most recognizable works and the ones that cemented his association with Pop — are clearly not just that when you see them in person. Their impasto surface is as thick as the dunes of a real cake, while the oil paint “frosting” is lush, rich, inviting — and gestural, clearly marking the hand of the artist. What’s more, the exhibition convincingly demonstrates that Thiebaud’s cakes owe as much to Degas’s hats as they do to peppy and pretty American advertising.It strikes me that maybe a further reason Thiebaud has been labeled Pop might come down to geography. A West Coast artist producing images of cakes and candy in the second half of the 20th century was generally assumed to be capturing a Hollywood version of sunlit and superficial California. While some play is apparent, though, there is no irony in Thiebaud’s depictions of contemporary people, places, and things. And while he is often considered a “California artist” (a label he disliked), he believed that art transcended place, insisting, “There is only one art world and one painting world.” And that world is unquestionably where you can find him.Wayne Thiebaud “Display Cakes” (1963), oil on canvas; San Francisco Museum of Modern Art (© Wayne Thiebaud Foundation / Licensed by VAGA at Artists Rights Society (ARS), NY; photograph: Don Ross, Katherine Du Tiel)Wayne Thiebaud, “Office and Shopping Mall” (2005/2021), oil on canvas (photo Bridget Quinn/Hyperallergic)Wayne Thiebaud, “Road Through” (1983), oil on canvas (photo Bridget Quinn/Hyperallergic)Wayne Thiebaud “Five Seated Figures” (1965), oil on canvas; Wayne Thiebaud Foundation (© Wayne Thiebaud Foundation / Licensed by VAGA at Artists Rights Society (ARS), NY)Wayne Thiebaud: Art Comes from Art continues at the Legion of Honor (100 34th Avenue, San Francisco, California) through August 17. The exhibition was curated by Timothy Anglin Burgard.