The first ghost to leave the world of the dead was Roger. He took a step forward, and turned to look back at Lyra, and laughed in surprise as he found himself turning into the night, the starlight, the air...and then he was gone, leaving behind such a vivid little burst of happiness.

The Amber Spyglass (ed. Knopf Books for Young Readers, 2007) - ISBN: 9780375846731