Are there difficulties and dangers for the Westerner in Indian yoga? The answer is that this is true of some kinds of yoga technique but not of all, and for many Westerners but not for all. I have come across many cases during my travels where aspirants have wrecked health or mind through plunging blindly into yoga, and this is equally true of Indians themselves. It has always been my endeavour to protect readers of my books by communicating only what I know to be safe methods. I have deliberately kept silent about the others. However, if the student keeps his feet on earth, if he does not renounce common sense and a balanced life, and if he stops practising if untoward signs should ever appear and consults an expert about them, there is really little to fear. Most of the people who have gone astray though yoga have been neurotics, fanatics, and the mildly insane.
-- Notebooks Category 5: The Body > Chapter 5: Exercise > # 104