A beautiful face is at all time pleasing to the eye, but then especially when there is joy manifested in the countenance. Joy in the face puts a new beauty, and makes that which before was beautiful to be exceeding beautiful. It puts a lustre and glory upon beauty; so does joy in the face, heart, and life of a Christian, cast a general splendor and glory upon him, and the ways of God wherein he walks. The joy of the Lord is not only the strength, but also the beauty and glory of Christians. (see Nehemiah 8:10)
– Thomas Brooks –
from Heaven on Earth: A Treatise on Christian Assurance, 1654