[avixz]

Thanks Cyclamen great translation, this would be mine:

[That is] The principle of fair exchange, for the sake of obtaining something, something of equal value is necessary ことを示している。That is 教訓なのだろうか

What about that second part, can you fill the gaps with explanations?

I guess the と in それと doesn't have a direct translation here so "something of equal value" or "something else with the same price" seems appropiate