Graciela Iturbide, one of Latin America's most celebrated photographers, has spent more than five decades turning her gaze on Mexico's rituals, landscapes and people. At 80, she remains as uncompromising as ever. "Working with my heart is the only rule – nothing else," she says in a new interview with The Guardian.

It is a deceptively simple credo for a body of work that has become foundational to the history of photography. Iturbide, born in Mexico City in 1942, studied under the modernist master Manuel Álvarez Bravo before finding her own path — one that took her from the deserts of Sonora to the markets of Oaxaca, from Juchitán to the United States, and through long collaborations with the communities she photographed.

Her breakthrough came in the late 1970s with Mujeres Ángel, a photograph of a woman in a long dress descending a dune in the Sonoran Desert, shopping bag in hand, that has become one of the most reproduced images in Mexican photography. The picture distilled what Iturbide does best: the surreal embedded in the everyday, the mythic quality of ordinary movement, and a deep respect for her subjects.

Her series on Juchitán, in the southern state of Oaxaca, made between 1979 and the mid-1980s, cemented her reputation. There she photographed the Zapotec women who ran the town's commerce and social life, including the iconic Magnolia con espejo — a portrait of a man in a dress holding a mirror to his face, gazing at his own reflection. The series was a study of a matriarchal society that upended expectations of gender in Mexico at the time.

Iturbide's work has always hovered between documentary and poetry. She photographed the dead in cemeteries during Día de los Muertos, the masks of Mexican wrestlers, the bodies of birds arranged by a taxidermist in the Sonoran town of La Frontera. She has said she is not interested in "testimony" alone — the image must transcend the moment of capture.

"Working with my heart is the only rule – nothing else," she repeats, and it is a philosophy she has carried through every project, whether photographing Frida Kahlo's belongings for a museum commission or making portraits of Mexico's indigenous communities.

Now in her ninth decade, Iturbide continues to photograph, to travel and to resist easy categorization. Her archive and her influence continue to grow, with her prints held by major museums across the world and a new generation of photographers citing her as a formative influence. The heart, it seems, still leads the way.