The use of light and mixed materials (marble, bronze, paint, stucco) may reflect the influence of Bernini's Cathedra Petri in St Peter's Basilica, Rome.
According to American writer James Michener's book Iberia (1968), the Transparente was installed to allow light to pass from the ambulatory behind the high altar (or 'reredos' as he calls it), onto the tabernacle (the container for the Blessed Sacrament) which stayed in constant shadow because of the tall reredos.
After the two holes were cut, Tomé and his sons designed a way to visually connect them by sculpting a fantastic company of angels, saints, prophets, and cardinals.
Abstract designs suggesting flowing robes and foliage hang over corners to mask the details of the architectural piercings.
Intricate groups of figures were assembled so that the opening to the tabernacle could be hidden yet permit light to pass through.