" The thick crust of the early pie acted like a baking dish. For hundreds of years, it was the only form of baking container - meaning everything was pie. The crust also, as it turned out, performed two other useful functions: it acted as a carrying and storage container (before lunch boxes) and, by virtue of excluding air, as a method of preservation (before canning and refrigeration). "

― Janet Clarkson, , Pie: A Global History