"Nienna looked at the pale Moon under the shadow of her distant halls. She remembered the glory of the Two Trees and all the pain that Melkor caused by his greed and envy. But in silence she evoked the Music of The Ainur and how Melkor's actions were present even there, as a terrible melody in the middle of unfolding mysteries. And as she revived the Music in her thoughts, her sorrow grew but so did her compassion. For Nienna is the mighty one who cries for all the unjust and terrible things that happen in the world, but she is also the one that teaches endurance and wisdom through adversity. And by her tears, everything is purified and hallowed so that the mysteries can dance with the Music as it unfolds."
Nienna, from J.R.R. Tolkien's legendarium.