These two verses are built around a difficult figure. The treachery of your enemy is compared to a bronze mirror. Mirrors, in ancient times, were made of polished bronze. Bronze corrodes, and when a bronze mirror corrodes, you cannot see clearly in it. It has to stay polished. Ben Sira says here that you have to be constantly on guard against a false friend or an enemy if you want to be able to see what he is doing. He is like the mirror; you have to keep it constantly polished if you want to be able to see in it. This is what translators need to keep in mind as they work with these verses.

Never trust your enemy, for like the rusting of copper, so is his wickedness: Copper is better rendered “bronze” or even “brass.” It does not rust; it corrodes. Rust is found only on iron or steel. The Greek term for rusting is general; English requires more precision. Translators may be working with a language that can also use a general term. Good News Translation avoids the problem by not mentioning the specific metal here; it simply speaks of “rust,” trusting that the reader knows rust affects metal. This sentence does not mean that an enemy’s wickedness is as certain as the corrosion of bronze. It means that an enemy’s wickedness may be compared to corroding bronze, in a way that will be specified in the next verse. Good News Translation expresses the point of the comparison as the destructive nature of both an enemy and corrosion. This is not quite the point, but it is not inconsistent with the author’s point. However, Contemporary English Version‘s comparison in verses 10-11 is better:

• Never trust your enemies—
their evil will attack you
like rust eating away
at an unpolished mirror….

Even if he humbles himself and goes about cringing: This refers to the false friend who puts on a show of being innocent and modest, perhaps being flattering. The Greek word translated cringing refers to assuming a submissive posture. New Jerusalem Bible has “bowing and scraping.” In modern English-speaking societies people do not ordinarily assume such postures, so Good News Translation simply says “even if he acts ever so humble,” but in many societies language showing cringing behavior will be appropriate here; for example, “even if they bow down and act humble” (Contemporary English Version).

Watch yourself, and be on your guard against him: The warning here is stated twice in this line, partly no doubt to fill out a poetic line in the original Hebrew, but it also provides emphasis. Good News Translation does well to preserve it: “Watch out, and be on guard against him.” Good News Translation reverses this line and the preceding one since it is more natural in English to begin with the imperatives. Contemporary English Version is similar with “So be on guard against them.”

And you will be to him like one who has polished a mirror: This means “you must treat him as you would treat a bronze mirror that needs polishing”; that is, you must take constant care that you can see clearly. In the case of your false friend, you must keep the film of his hypocrisy wiped away so that you can see him as he really is. Mirrors were made of bronze in the author’s time. It was a metal that would take a smooth polish. But in cultures where bronze is unknown, we may say “You must treat him as you would treat a metal mirror that needs polishing.” In cultures where metal mirrors are unknown, we may say “… as you would treat a mirror that needs to be wiped clean.”

And you will know that it was not hopelessly tarnished: The Greek of this line is obscure, and each translation seems to understand it differently. The Hebrew is completely different, and consequently of no help. We take it to mean “to keep it from being completely tarnished/corroded.” In other words, if you don’t keep the mirror polished, eventually you will not be able to see anything at all. Compare An American Translation: “And you must make sure that it is not all covered with rust.” Another possible rendering is “You must make sure that it is free of dirt.”

As a model for these two verses, we offer:

• Never, never trust an enemy. Even if he acts harmless and innocent, watch out, and be on guard against him. You must continually polish a metal mirror to keep it from getting so corroded that you cannot see your image in it. In the same way keep watching your enemies and what they are doing.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.