Boasting: see the comment on 4.18.

Not good: the text also suggests the meaning “not pleasant (to listen to).”

Other ways of rendering Your boasting is not good are “You should not be proud” or “You have no reason to be proud.”

Do you not know…? or “Don’t you know…?” is a phrase that Paul often used in reminding his readers of what they had already been taught (see 3.16; 6.2, 3, 9, 15, 16, 19). This rhetorical question is equivalent to a strong statement: “Surely you know…,” “Surely you have heard what is said in the past,” or “I am sure that you are familiar with the saying….”

Some biblical metaphors or figures of speech may be changed if necessary in translation, but the metaphor of leaven or “yeast” (Good News Bible) is so deeply rooted in Old Testament events and traditions that it must be kept here. If necessary the translator may have a footnote or a note in a glossary explaining this metaphor. A good example is the note on “yeast” in the Good News Bible Word List. Paul refers to some of these Jewish traditions in verses 7 and 8. In this passage, one aspect of the metaphor “yeast” suggests another aspect. In verses 6b, 7a, 7b, and 8, four different ideas are expressed with the language of “yeast” as the only link between them. Verse 6b, which may have been a proverb (compare Gal 5.9), contrasts the small amount of yeast with the much larger lump of dough that it causes to rise. The next verses go on to show that this effect is bad (contrast Matt 13.33 and Luke 13.20-21, which give a good meaning to the effect of yeast).

Quoted with permission from Ellingworth, Paul and Hatton, Howard A. A Handbook on Paul’s First Letter to the Corinthians, 2nd edition. (UBS Handbook Series). New York: UBS, 1985/1994. For this and other handbooks for translators see here .