Gaudí used light to bring out the splendour and expressiveness of his
architecture. Rays of light make the pinnacles that top the towers and
windows shine. The sun in the east illuminates the portals on the Nativity
façade and accentuates the joy of life that is the birth of Jesus. On the
Passion façade, the contrasting light and shadows from the setting sun
makes it feel even coarser and harsher. While on the Glory façade, the midday
sun will make the sixteen lanterns on the monumental narthex shine and
illuminate the main entrance to the Basilica. And the purpose of this light
shining harmoniously into the interior of the Temple is none other than to convey
the presence of God.