A jealous wife's sarcasm
When Chinese talk about basic groceries or things needed in order to live, they would often use the proverb "the Seven Necessities", which refers to firewood, rice, oil, salt, sauce, vinegar, and tea. This proverb has the same meaning as "Bread and Butter" in English.
The earliest mentioned of such words was in a Yuan Dynasty play (Yuan Dynasty, 1206-1368, a empire started by Genghis Khan), in which a dialogue saying, "Get up in the morning, open the door first, and think about the seven necessities, firewood, rice, oil, salt, sauce, vinegar, and tea". So the proverb could also been said as "Open Door Seven Necessities".
From this proverb we could understand that tea was a popular drink in old China. In the past, tea was consumed as a daily drink, when people talked about poverty, they would say such thing as "the household even couldn't afford tea, and have to drink plain water." A host/hostess would apology to his/her guests if they could not serve tea to them.
In Ming Dynasty (1368-1644), a man married a concubine despite his wife's objection. - In old China, men were allowed to marry concubines without the consent from his wife. Those married concubines have lesser legal rights and lower social status, and so does their children. Those women were called "Qie" in Chinese, while the wife was called "Qi"- Back to our story, the angry wife wrote a poem upon his husbands' marriage with the "Qie" as a wedding gift.
"Congratulation on your getting a new bride
I will wash my hands off household works
Pass to her all those open door necessities
Firewood, Rice, Oil, Salt, Sauce and Tea"
In this poem, when the wife talked about passing those open door necessities to the concubine, she purposefully left out the item "Vinegar". In Chinese, the connotation of jealousy is "drinking vinegar", she was express her jealous by indicating that she kept the vinegar for her own consumption.
