While the other interpretations are interesting, and could be others, I think iconography of one of the first recorded human civilizations, the pyramid, is a metaphor for society's indoctrinating effect on individuals. The baby is a metaphor for personal identity, taken away as it becomes part of the collective, leaving the chorus as a kind of wailing dirge for one's lost sense of identity, birth, and death, concealed by the "Mask" imposed by society, the Pyramid casting its shadow. The electronic and kind of droning music reinforces the idea of a machine processing individuals into society's more generic products.
While the other interpretations are interesting, and could be others, I think iconography of one of the first recorded human civilizations, the pyramid, is a metaphor for society's indoctrinating effect on individuals. The baby is a metaphor for personal identity, taken away as it becomes part of the collective, leaving the chorus as a kind of wailing dirge for one's lost sense of identity, birth, and death, concealed by the "Mask" imposed by society, the Pyramid casting its shadow. The electronic and kind of droning music reinforces the idea of a machine processing individuals into society's more generic products.