The main risk of “an eye for an eye, and a life for a life” is the risk of wrong punishments that cannot be reversed. On the other hand, when someone has cause

The main risk of “an eye for an eye, and a life for a life” is the risk of wrong punishments that cannot be reversed. On the other hand, when someone has caused an irreparable damage, by causing death or permanent invalidity, or by destroying something that cannot be recreated, e.g. an ancient historical artifact, or an entire animal species, then being punished in a limited way, e.g. with a fine or some time in prison, does not seem equivalent with the punished deed. I believe that punishment by prison is extremely stupid and inefficient. In many places prisons are more like criminal academies than something that may educate the inmates to no longer do what they have been punished for. No wonder that in the ancient societies this kind of punishment was unknown. In many ancient societies the main method of punishment was a fine, but in order to be a true deterrent the value of the fine was always a multiple of the damage that had been caused. In more lenient societies a thief or someone who had caused property or body damage would have payed a sum equivalent with the double of the damage value, but in more severe societies the fine was quadruple and in some societies the fines were even ten times greater than the estimated value of the damage. Such a multiple-valued fine seems a much better punishment than any kind of prison, for any kind of damage that can be repaired. For the other damages, like death or permanent invalidity, the appropriate punishment would seem to be the obligation to periodically pay some amount for the rest of the life of the punished person, instead of paying a one-time fine. In the ancient societies, the cases when a punished person was unwilling or unable to pay the fine were solved simply, by converting that person into a slave. Such cases would be more difficult to solve in a modern society, but spending time in a prison cannot be considered as an improvement over slavery.