Remember that line from your childhood?  "Cross my heart and hope to die, stick a needle in my eye...."  Who comes up with this stuff?  As children we used that line as an oath to guarantee we were telling the truth.  People finally grow out of that stage and start saying things like, "It's the gospel truth" or "I swear to God" or "On my mother's grave I swear" etc.  You may not think these are important matters to be dealing with but Jesus thinks they are.  In His manifesto He taught the disciples that truth telling and keeping our word is imperative.  Again, imagine a society that actually took Jesus' brilliant advice to heart?  If we, by His grace, eliminated anger, contempt, refusal to reconcile, lust and unjustifiable divorce from our every day life, our culture would be transformed.  And, add to that a "yes" that actually meant "yes" and a "no" that actually meant "no" and police and courtrooms might actually be looking for stuff to do instead of being overcrowded.  Lies, manipulation with words and broken promises have become so much a part of our culture that people are understandably cynical and suspicious.  But the church is to be the "pillar and foundation of the truth."  If we don't look different than the culture around us, we are going to have a hard time communicating the gospel truth.  Sometimes, telling the truth and keeping our promises is inconvenient and it even costs us money.  We must remember that the Kingdom of Heaven us among us, we have a generous Father who cares for us and we are His dearly loved children.  Christ wants us to become the kind of people who never need to swear by anything...we must simply give our word and do what we have said.  The more we meditate on the reign of God that is "among us", the more such a lifestyle will seem right...and possible!