What sets you free - at least that's apparently what it's supposed to do. Sometimes it hurts on the ears and can be very hard to swallow, but most of us can smell it from miles away. Sometimes it is even capable of making one feeling hundreds of pounds lighter in a single utterance.
Either way you put it, it consists of factual statements that usually tend to create the path of least resistance when it comes to keeping one's story straight. Whether that story is good or bad.