Hi Berean:

I see your answer about the abounding of the law. Am I then missing something in translation or tradition? For the two seems very opposite. One says eye for an eye and life for life, but Yeshua use the word 'but I tell you', as if he is saying something different.

I thought I would address this first:
I suppose you could say that Yahshua is saying something different, but actually He is saying something higher.
I'll explain from an vibratory standpoint.
Negative emotions have low vibratory wavelengths, you know things like hate, fear, violence, pride and all things negative. Whereas the higher emotions have a very high vibration, love, gratitude, peace, joy, beauty and all things wonderful.
So when Yahshua says, but I say unto you ...love your enemies.' From a purely energetic standpoint what is happening is this, If I receive a negative instance from someone and I return a negative instance all I have done is perpetuate the negative, kind of like creating a dark, negative vortex, a whirlpool if you will that sucks both participants into it's grip.
On the other hand if I return positive for negative,
i.e. someone whacks me on the cheek, and I give the other cheek, then what happens is this...I transmute or reverse the flow of negative energy, or rather I create within myself a whirlpool of light that washes the dark energy away from myself.
So simply an 'eye for an eye or a blow for a blow, only stops the dark energy in it's track but kind after kind does not reverse the flow.
It helps to see this illustration in the form of rivers or streams. In the Mosaic law, the river is dammed up for the time being, but with what Yahshua instructed the river is reversed.
Other analogies would be something like this, positive for negative is a form of transmutation.
Anyway the point is, is that you want to stay in higher vibrations, so in order to do this it is necessary to return light for darkness.

Michael