"What is it that is more precious than anything else to a person?
Money? Pleasure? Power?
As the Talmud story of Rabbi Abahu describes: His face shone with great beauty and joy because he had come upon a new explanation to an old Mishnaic text.
The soul's fulfillment causes a radiance to shine forth from a person.
The priestly blessing says: "May the Lord let His countenance shine upon thee" (Numbers 6:25).
What does this mean?
After all, God looks upon all men on earth, and His Presence is always with us.
But He does not always smile —and the invocation to let His face shine upon us is the expression for such a need.
When we meet someone we love in the street, there is no need for words;
immediately there is the smile of the heart's recognition.
The eyes speak before the tongue has found words.
The inner light is readily emitted."
From In the Beginning, p.281, by Rabbi Adin Steinsaltz