A legend told by the Venerable Bede says that the poet Caedmon was once completely mute. It was a custom in his village to spend evenings taking turns reciting poetry. On these occasions, Caedmon, unable to speak, would steal away to nearby hills to escape. One evening while walking alone, an angel appeared and urged him to sing. Miraculously, he began to sing and went on the become a famous poet.
Look at this window: it is nothing but a hole in the wall, but because of it the whole room is full of light. So when the faculties are empty, the heart is full of light. Being full of light it becomes an influence by which others are secretly transformed.