And if by lack of strength he is prevented from sinning: Strength is literal; it probably means “opportunity” in this context, so Good News Translation renders this line as “If for some reason they are unable to sin now.” “For some reason” represents nothing in Greek, but is a natural addition in English.

He will do evil when he finds an opportunity: Opportunity is literally “an [appropriate] time.” For the whole line Good News Translation says “they’ll get around to it [sinning] at the first opportunity,” which is effective but highly idiomatic English.

An alternative model for this verse is:

• This person might not be able to sin now, but he will do so when he thinks the time is right.

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.