I love this, from the Academy of American Poets newsletter:

 
'This week’s poetic term from Edward Hirsch is lullaby: “Rodrigo Caro called these soothing melodies, which are found all over the world, the ‘reverend mothers of all songs.’ Federico García Lorca noted that ‘Spain uses its very saddest melodies and most melancholy texts to darken the first sleep of her children.’”'