At its simplest, a sandwich is two slices of bread enclosing a filling.

NPR: The Art Of Sandwich-Making

According to popular legend, the sandwich was invented by John Montagu, the fourth Earl of Sandwich, who, while gambling, told his butler to put some meat between two slices of bread so he could eat without interrupting the game and getting grease on the cards.

NPR: The Art Of Sandwich-Making

No extra calories are needed during the first 28 weeks of pregnancy and only an extra 200kcal per day are required during the last 12 weeks, the equivalent of two small slices of bread.

BBC: Fat, pregnant or both?

It was always the same: a great wedge of papaya with limes, a crisp thin omelette with green chilis mixed in, two slices of inch-thick white-bread toast, a dollop of red jelly and of margarine, and a pot of coffee with milk.

CNN: From Our Correspondent: On a Magical Hill