Who was lost on a painted sky where the clouds are hung for poets eye?

This is a line from the song "The Sound of Silence" by Simon & Garfunkel.

The line is "Hello darkness, my old friend / I've come to speak with you again..."

The "painted sky" and "clouds hung for poets' eye" imagery is a metaphor for the beauty and mystery of the world, and how the speaker feels alienated from it. He is seeking solace in the darkness, which represents isolation and introspection.