John MacArthur, James, Moody Publishers, 1998, p. 144.
The tongue is you in a unique way. It is the tattletale on the heart and discloses the real person. Not only that, but misuse of the tongue is perhaps the easiest way to sin. There are some sins that an individual may not be able to commit simply because he does not have the opportunity. But there are no limits to what one can say, no built-in restraints or boundaries. In Scripture, the tongue is variously described as wicked, blasphemous, foolish, boasting, complaining, cursing, contentious, sensual and vile. And that list is not exhaustive. No wonder God put the tongue in a cage behind the teeth, walled in by the mouth!
John MacArthur, James, Moody Publishers, 1998, p. 144.