Hidden wisdom and unseen treasure, what advantage is there in either of them?: Good News Translation restructures this rhetorical question well by saying “Wisdom that is not expressed is like a treasure that has been hidden—both are useless.” Another approach is:

• If you do not use your wisdom, it does no more good than hidden [or, buried] treasure that no one ever finds.

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.