"In Egypt the gates of the under world through which the sun passes are shown in the illustrations to the Book of the Dead as great pylons like the entrances to the temples. Every temple pylon becomes a sun gate, and sculptured and painted on the centre of its lintel is the red disc of the sun. 'The winged globe,' says Wilkinson, 'always having its place over the doorways.' And Perrot and Chipiez, 'It was generally ornamented with the winged globe, an emblem which was afterwards appropriated by the nations which became connected with Egypt. This emblem in its full development was formed by the solar disc, supported on each side by the uræus, the serpent which meant royalty. The disc and its supporters are flanked by two wide-stretching wings with rounded fan-shaped extremities, which symbolized the untiring activity of the sun in making its daily journey from one end of the firmament to the other. Egyptologists tell us that the group as a whole signifies the triumph of right over wrong, the victory of Horus over Set (light over dark). An inscription at Edfou tells us that after this victory Thoth ordered that the emblem should be carved over every door in Egypt, and in fact there are very few lintels without it.' That is, there was a sacred legend saying that the God of Wisdom ordered the sun to be represented on every portal, to symbolise the victory of the sun over darkness, in the struggle at daybreak at the gates of the east."
Excerpted from:
Architecture, Mysticism and Myth, Chapter VIII, “The Golden Gate of the Sun”
by W.R. Lethaby, [1892], pp. 176-177.