The concealed foot
At the base of the 9th-century Borobudur monument, a complete section of the structure remains hidden from view, encased in a massive stone buttress. This concealed level, known as the "hidden foot," was first discovered in 1885 by the Dutch engineer J.W. IJzerman. It contains a series of 160 carved stone panels that wrap around the monument's original base. These are the Karmawibhangga reliefs, a visual record of the Buddhist law of cause and effect.
The reliefs form a narrative gallery illustrating the concept of karma. Each panel shows a specific action, from gossip and murder to charity and piety—and its resulting consequence in the cycle of life, death, and rebirth (samsara). The panels show worldly desires and their outcomes, showing thieves, adulterers, and those who inflict violence receiving torturous punishments in the afterlife, while the virtuous are rewarded. The carvings also provide a record of 9th-century Javanese life, depicting local agriculture, architecture, and social customs with precision. Some panels contain short inscriptions in Sanskrit, believed to be instructions for the carvers. Before the entire level was re-covered for preservation, the full series of 160 reliefs was documented in photographs between 1890 and 1891.
An ancient engineering dilemma
Why the builders of Borobudur entombed this extensive gallery of reliefs remains a subject of intense scholarly debate. The two primary theories involve structural necessity and religious or aesthetic choice. One perspective suggests the encasement was a purely engineering-based decision. The original design, built around a natural hill, may have been too heavy. As the upper terraces were constructed from an estimated 56,600 cubic meters of volcanic stone, the lower section might have begun to bulge and slide outwards. Adding a broad, sloping casement base, about 6.5 meters wide, would have served as a buttress to prevent a catastrophic structural failure.
The alternate theory proposes a religious or aesthetic motivation. The Karmawibhangga reliefs, with their graphic depictions of earthly desires and punishments, belong to the cosmological field of Kāmadhātu (the world of desire). Some scholars argue that a later architect or religious authority deemed these scenes too profane for the base of such a sacred monument. The decision to cover them may reflect a desire to direct pilgrims' minds away from worldly matters and toward the more enlightened realms on the upper terraces. This suggests a deliberate theological choice to hide the graphic scenes of negative karma, effectively purifying the monument's exterior and focusing the spiritual path upwards towards enlightenment. Evidence for this idea includes signs that some reliefs were partially chiseled away before the entire section was finally buried.