“Having devoted the greater part of my life to visiting and studying the various Native Races of North and South America, and observing the healthy condition and physical perfection of those peoples in their primitive state, I believe I have discovered the cause of numerous health problems that exist in our civilized communities. I believe, and feel authorized to assert, that a great proportion of the diseases prematurely fatal to human life, as well as mental and physical deformities, and destruction of the teeth, are caused by abuse of the lungs, in the Mal-respiration of Sleep.

“Quiet and natural sleep is the great physician and restorer of mankind; but the habit of sleeping with the mouth open is destructive to the human constitution. Man’s cares and fatigues of the day become a daily disease, for which quiet sleep is the cure; and the All-wise Creator has so constructed him that his breathing lungs support him through that sleep, like a perfect machine, regulating the digestion of the stomach and the circulation of the blood, and carrying repose and rest to the utmost extremity of every limb; and for the protection and healthy working of this machine through the hours of repose, He has formed him with nostrils intended for measuring and tempering the air that feeds this moving principle and fountain of life; and as the quieting and restoring influence of the lungs in natural repose is carried to every limb and every organ, so in unnatural and abused repose, do they send their complaints to the extremities of the system, in various diseases; and under continued abuse, fall to pieces themselves.

“There is no animal in nature, excepting Man, that sleeps with the mouth open; and with mankind, I believe the habit, which is not natural, is generally confined to civilized communities, where he is nurtured and raised amidst enervating luxuries and unnatural warmth, where the habit is easily contracted, and in sudden changes of temperature, even in his own house. Through the enjoyment of his artificial comforts and pleasures, he is destroying his teeth, his good looks, and often his life, in the thoughtless departure from natural simplicities and instincts. Man, who suffers under many ills in life, should take care that his lungs and teeth, however much abused during the day, should at least be treated with kindness during the night. Breathing should be done as Nature designed it, through the nose.

“There is no perfect sleep for man or brute, with the mouth open. When you close your eyes to sleep, close your mouth too, only to be opened after your eyes and ears in the morning. Though the majority of civilized people are more or less addicted to the habit of sleeping with the mouth open, few will admit that they are subject to it. They go to sleep and awake, with their mouths shut, not knowing that the insidious enemy, like the deadly Vampire that imperceptibly sucks the blood, gently steals upon them in their sleep and does its work of death whilst they are unconscious of the evil. Every physician should advise his patients, and every school its pupils, and every hospital, regiment, nursery, and mother should attempt to stop this unnatural and dangerous habit.

“If I were to endeavour to bequeath to posterity the most important Motto which human language can convey, it should be in three words:  Shut—your—mouth.”

—George Catlin, The Breath of Life and Shut Your Mouth, 1860s, abridged