Quaestiones Naturales

Is it because the changing of the sweet must into wine is concoction, but cold hinders concoction, because this is caused by heat? Or, on the contrary, is the proper taste of the grape sweet, and is it then said to be ripe, when the sweetness is equally diffused all over it; but does cold, not suffering the heat of the grape to exhale, and keeping it in, conserve the sweetness of the grape? And this is the reason that, in a rainy vintage, must ferments but little; for fermentation proceeds from heat, which the cold does check.