Gerardo Murillo (1875–1964), better known as Dr. Atl, was a pivotal figure in Mexican art, recognized for his contributions to landscape painting, particularly his depictions of volcanoes, and for his mentorship of influential artists such as Diego Rivera or Cordelia Urueta. However, beyond his renowned work in vulcanology and his impact on the Mexican muralist movement, Murillo was deeply involved in esoteric circles, which significantly influenced his artistic vision.

Murillo’s engagement with esotericism can be traced to his collaboration with Arnold Krumm-Heller, a German occultist and founder of the Fraternitas Rosicruciana Antiqua in Latin America. Together, they played a role in organizing the Red Battalions, a group of workers' militias allied with Venustiano Carranza that fought against the forces of Pancho Villa and Emiliano Zapata during the Mexican Revolution. This connection underscores how Murillo, like other intellectuals of his time, integrated esoteric and revolutionary ideals into his broader cultural and artistic projects.

Murillo’s interest in spiritual themes extended into his mural work, particularly in his allegorical paintings at the Former Jesuit Temple of Saint Peter and Saint Paul (Ex-Templo de San Pedro y San Pablo). These murals, which have since been destroyed, depicted cosmic and elemental forces through nude allegorical figures. His representations of the Sun, Moon, Rain, and Night evoked spiritual themes, portraying celestial and natural elements as anthropomorphic, divine beings.

Murillo’s murals at San Pedro y San Pablo shared thematic similarities with those of Roberto Montenegro, whose own Allegories series, painted in the same Temple, were also removed. The original version of Montenegro’s Tree of Life similarly included nude figures, which were later censored to align with the state’s ideological emphasis on nationalist grandeur and epic historical narratives.

The disappearance of Murillo’s murals illustrates a broader pattern in post-revolutionary Mexico: while muralism was a state-sponsored project, spiritual and esoteric themes that did not conform to the nationalist and heroic ethos of the era were often sidelined. Murillo’s cosmic and allegorical works, which emphasized universalist and spiritual themes rather than revolutionary epic narratives, did not fit within the dominant discourse of Mexican identity promoted by the state.

Despite this marginalization, Murillo’s visionary depictions of volcanoes as spiritual entities continued to shape modern Mexican art. His legacy endures not only in his influence on Rivera, Orozco, and Siqueiros but also in his unique integration of esoteric and revolutionary thought, positioning him as a key figure in the intellectual currents that flowed through Mexico’s post-revolutionary artistic landscape.

Although the murals themselves were destroyed, their imagery has been preserved thanks to their publication in México en pensamiento y en acción (México in Thought and in Action), an illustrated volume featuring the pictorial work of José Clemente Orozco, Diego Rivera, and Dr. Atl, edited by Rosendo Salazar and published by Editorial Avante in 1926.