I have a copy of the Desiderata on my reading room's door and it probably is a piece of prose that I refer to and reflect on more than any other.
It was written by Max Ehrmann, although many have the misconception that it is anonymous.
I keep it in a place where I can glance at it from time to time and often a particular line seems to jump out at me, my favorite being "You are a child of the universe, no less than the trees and the stars, you have a right to be here". It seems that whatever I may be going through, the words of this piece always give me peace and quite often an answer.
I will not post it in it's entirety as it is copyrighted material, but I did find a slide show from Youtube with the words in it so I'll share that: