An excerpt from The Mind: Its Projections and Multiple Facets by Yogi Bhajan (page 71)
The greatest blunder that almost everyone makes is the feeling that you have to speak whatever is on your mind. That doesn't make sense. Your language becomes a loudspeaker and you sound like a squawking duck. The mind has automatic waves of thought and feelings from many sources. You are not meant to speak all of that. The mind is meant to know the truth. Train your mind to speak the truth in a committed language so it is beautiful and effective.