In Wilhelmine Germany, where Planck lived, the day is structured into four parts: a breakfast (Frühstück) of bread and coffee, the hot midday Mittagessen which is the main meal, the afternoon ritual of Kaffee und Kuchen (coffee and cake), and finally Abendbrot — a cold supper of breads, cold cuts, and cheeses. Hot food is eaten at midday, cold food in the evening: the opposite of the French table.

From the dense crumb of Roggenbrot to sour cabbage (Sauerkraut) and Berlin's tart beer, northern German cuisine relies on sour-fermented foods: preserving, acidifying, leavening with sourdough. It is the thread that connects Planck's frugal table, from daily bread to the evening glass.