Desiderata (the original version with proper attribution)

Desiderata has been popular for the past few decades, though its original version and the story behind it were blurred by false attributions.
What follows is the original version, its proper attribution and the story of the hoax that surrounded the piece.

Desiderata (the real version, with corrected attribute to follow)
Go placidly amid the noise and the haste, and remember what peace there may be in silence. As far as possible without surrender be on good terms with all persons. Speak your truth quietly and clearly; and listen to others, even to the dull and the ignorant; they too have their story. Avoid loud and aggressive persons, they are vexatious to the spirit.
If you compare yourself with others, you may become vain or bitter; for always there will be greater and lesser persons than yourself. Enjoy your achievements as well as your plans. Keep interested in your own career, however humble; it is a real possession in the changing fortunes of time.
Exercise caution in your business affairs; for the world is full of trickery. But let not this blind you to what virtue there is; many persons strive for high ideals; and everywhere life is full of heroism. Be yourself. Especially, do not feign affection. Neither be cynical about love; for in the face of all aridity and disenchantment it is as perennial as the grass. Take kindly the counsel of the years, gracefully surrendering the things of youth.
Nurture strength of spirit to shield you in sudden misfortune. But do not distress yourself with dark imaginings. Many fears are born of fatigue and loneliness. Beyond a wholesome discipline, be gentle with yourself. You are a child of the universe, no less than the trees and the stars; you have a right to be here. And whether or not it is clear to you, no doubt the universe is unfolding as it should.
Therefore be at peace with God, whatever you conceive Him to be. And whatever your labors and aspirations, in the noisy confusion of life keep peace in your soul. With all its sham, drudgery and broken dreams, it is still a beautiful world. Be cheerful.
Strive to be happy.
- Max Ehrmann (September 26, 1872 - September 9, 1945), an attorney from Indiana, was best known for writing the Desiderata (Latin: something desired as essential) in 1927.

The Baltimore hoax
In about 1965 copies of the poem were circulated to various publications with the fraudulent (or perhaps simply mistaken) attribution "Found in Old Saint Paul's Church, Baltimore; Dated 1692", and it was widely reprinted on the assumption that it was in the public domain. Even Analog Science Fact / Science Fiction was taken in. On close analysis some of the concepts expressed in the poem seem too sophisticated for the 17th century, yet even today many people still believe the hoax.