The kiln tests the potter’s vessels: A kiln is the furnace or oven in which newly made pots of wet clay are put to be fired (baked). If there are flaws in the pot, it will crack during the firing. In cultures where “kilns” are unknown, this line may be rendered “When you bake a pot made of wet clay in the fire to harden it, you can see where its flaws are.”

So the test of a man is in his reasoning: Reasoning is better translated “talk” or “speech” in this context. New Revised Standard Version uses “conversation.”

Good News Translation‘s rendering of this verse is a bit awkward. Better models are the following:

• The way you talk shows your character as surely as any flaws in a clay pot will appear when the pot is fired [or, heated] in a kiln.

• … as surely as any flaws in a clay pot appear when someone fires [or, heats] up the pot in a kiln.

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.