Sistine Chapel ceiling identity of the figures in the lunettes and spandrels, continue to defy interpretation. Modern scholars have sought, as yet unsuccessfully, to determine a written source of the theological program of the ceiling and have questioned whether or not it was entirely devised by the artist himself, who was both an avid reader of the Bible and a genius. Also of interest to some modern scholars is the question of how Michelangelo's own spiritual and psychological state is reflected in the iconography and the expression of the ceiling. One such speculation is that Michelangelo was tormented by conflict between homosexual desires
Restoration of the Sistine Chapel frescoes have been predicted by previous restorers. One of the major dangers to the frescoes is automotive exhaust, and they are also vulnerable to the effects of the crowds of tourists that pass through the chapel every day, bringing with them heat, humidity, dust and bacteria (the latter of which can biodegrade paints and pigments). The clean plaster surfaces are more in danger from these destructive elements than they were when they were covered with a layer of smoky wax. Previously, the Sistine Chapel's only ventilation was from its windows in the upper level of the walls. To prevent exhaust fumes