"the political ferment produced new leadership"
"social unrest"

"The Middle East is fermenting"
"Her mind ferments"

"Islam is fermenting Africa"

"We ferment the grapes for a very long time to achieve high alcohol content"
"The vintner worked the wine in big oak vats"

"The milk has soured"
"The wine worked"
"The cream has turned--we have to throw it out"