Catena Aurea on John 9:1–7: Gregory the Great

Or thus: By His spittle understand the savour of inward contemplation. It runs down from the head into the mouth, and gives us the taste of revelation from the Divine splendour even in this life. The mixture of His spittle with clay is the mixture of supernatural grace, even the contemplation of Himself with our carnal knowledge, to the soul’s enlightenment, and restoration of the human understanding from its original blindness.