What does "the sky is the bread of the eyes " mean?

This quote is from Ralph Waldo Emerson:

"The sky is the daily bread of the eyes"

The Concord transcendentalists believed that nature was awe-inspiring and spiritually rejuvenating.

The reference to 'daily bread' surely refers to the Lord's prayer, and Emerson was saying that the eyes -- and soul -- feast on the beauty of the sky.