Here is the complete riddle:
I am the part of the bird that is not in the sky, who can drown in the ocean and yet remain dry. A last vestige of man that refuses to die. In mourning I am tossed at your feet to lie; I begin my job early, devouring your ankles and thighs. I work my way up, eating your legs to your waist. And though around midday away I am chased, I return quickly to savor the arm of my taste. As evening falls I enter your lungs, spiraling down past your mouth and your tongue. I feast on your body, your soul, and your mind, but as darkness falls you shall find that away I will go, a relief for some; At least until tomorrow morning comes. What am I?