Opinion by Joel Baden, special to CNN

(CNN) -- This past Sunday, six Israelis were arrested for the murder of a 16-year-old Palestinian boy. Israeli officials admitted the likelihood—already acknowledged by many—that this killing was carried out in revenge for the kidnapping and murder of three Israeli teenagers.

Both sides have stepped up their aggression in the past few days, with rocket launches from Gaza into Israel and Israeli airstrikes against Gaza.

It’s a familiar cycle: attack for attack, murder for murder. Such patterns are familiar from conflicts across the world, but they have a special resonance in the Holy Land.

After all, it was from Israel, nearly 3,000 years ago, that this famous concept spread.

The Book of Exodus in the Hebrew Bible says, “The penalty shall be life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burn for burn, wound for wound, bruise for bruise.”

The Book of Deuteronomy uses even stronger language: “Show no pity: life for life, eye for eye, tooth for tooth, hand for hand, foot for foot.”

And the Book of Leviticus says again, “Anyone who maims another shall suffer the same injury in return: fracture for fracture, eye for eye, tooth for tooth. The injury he inflicted on another shall be inflicted on him.”

Few biblical laws are repeated three times; this is one of those few. It is known as the lex talionis, or “law of retaliation,” and it would seem to be central to the biblical worldview.

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This law is often brought as evidence that the Bible cannot be a reliable guide for modern morality: Who today would truly advocate for this kind of retributive justice?

It seems barbaric that the penalty for arson, for example, would be burning the arsonist to death—this sounds like something out of the Middle Ages, not out of the 21st century.

Though famously biblical, lex talionis isn’t a biblical creation at all.

It was already present in the famous Code of Hammurabi, from the 18th century BCE: “If an upper-class man should blind the eye of another upper-class man, they shall blind his eye,” and so on through breaking bones, knocking out teeth, etc.

Earlier Mesopotamian law codes, two generations before Hammurabi, take what we would consider a more civilized approach to the matter:

“If a man bites the nose of another man and thus cuts it off” —don’t ask— “he shall weigh and deliver sixty shekels of silver; an eye, sixty shekels; a tooth, thirty shekels …”

It turns out that the oldest codes in the Near Eastern legal tradition, Sumerian laws from the 21st century BCE, also have payment in place of retaliation.

The concept of “eye for an eye” isn’t really representative of some primitive state of humanity—it’s actually a development from an earlier system of monetary compensation.

Yet it was not a permanent shift; some of the earliest interpreters of the Bible read the lex talionis as advocating for monetary compensation: the value of an eye for an eye.

This remains a very common interpretation even today—quite likely as an attempt to make the biblical custom seem less harsh in comparison to contemporary cultural and legal norms.

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In the Talmud, the fundamental Jewish legal text, there is an extended discussion about the phrase “eye for an eye,” with multiple rabbis arguing, and the text concluding, that the phrase means nothing other than financial compensation.

Eventually, in Judaism the literal reading of lex talionis came to be associated with heresy.

There is another important aspect of “eye for an eye” that is often overlooked: in the Bible, the law prescribes that the punishment be leveled against the offending individual by the state.

It is not permitted for the victim himself to turn around and inflict the same injury on the aggressor. On this the Bible and modern law agree.

But another biblical legal tradition provides the exception to this rule, and it too has enjoyed a long life down to the present: the idea that in the case of premeditated murder, someone from the family of the victim is appointed the “blood-avenger.”

The notion of putting a murderer to death is common enough even today (see: death penalty). But not so the idea that it is the obligation of the victim’s family, rather than of a central government.

This biblical passage enshrines in law the retaliatory instinct of anyone whose close relative has been injured. And it is this instinct that we see playing itself out in the Middle East today.

The problem, both between the two nations and for the rest of the world, is defining which side is playing which role. Both Israel and Gaza believe themselves to be the blood-avenger, and the other to be the murderer.

Yet even in the case of blood vengeance, biblical law at least keeps the system under the watchful eye of the elders, who arbitrate the claims of the respective parties, just as in the more direct cases of lex talionis.

Nowhere in the world is the Bible more alive and its traditions more present than in Israel and the Palestinian Authority, the lands from which the Bible emerged.

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As the conflict between the two parties worsens, yet again, comparisons with the kinds of retaliation and blood vengeance found in the Bible grow more and more apt.

And so, therefore, does the need for a third party to play the part of arbitrator: to settle the price of monetary compensation, to declare the terms of retaliation, and to put a stop to the cycle of blood vengeance.

That's a role the Bible calls for someone to fill -- and we're all still waiting.

Joel S. Baden is the author of “The Historical David: The Real Life of an Invented Hero,” and professor of Hebrew Bible at Yale Divinity School. The views expressed in this column belong to Baden.