John Szarkowski was about 13 when he saw an image by Dorothea Lange that “enormously impressed” him. After he had become the powerful director of photography at the Museum of Modern Art, he would recall that he took it to be a “picture of the hard-faced old woman, looking out of the handsome oval window of the expensive automobile with her hand to her face as though the smell of the street was offending her, and I thought, ‘Isn’t that marvelous?’ That a photographer can pin that specimen to the board as some kind of exotic moth and show her there in her true colors.”

A quarter of a century after his initial encounter with the photo, working in 1965 with Lange on his first one-artist retrospective at MoMA, he read her full caption for “Funeral Cortege, End of an Era in a Small Valley Town, California,” and realized that the fancy car belonged to an undertaker, and the expression he took for haughtiness was grief.

The wry confession of his mistake, which Szarkowski made in 1982 to an interviewer, is not mentioned in “Dorothea Lange: Words and Pictures,” which opened Sunday at MoMA. But it illustrates the curatorial theme: Lange’s pictures require verbal commentary to be read legibly.