The sun and The moon

Without pain you cannot appreciate happiness.

Every night the moon said to the sun "I love how you light up the universe.", and every morning the sun said to the moon "Oh how I love the way you darken the universe." The moon replied confused "How could a beauty like you love the darkness I bring?" The sun shined even brighter and said, "You and I fit perfectly into this universe because without you the universe would never appreciate me."