"When you unwrap it, break off a piece and stick it in your mouth, it doesn't remind you of the pyramids, a suspension bridge or a skyscraper; but chocolate, says materials scientist Mark Miodownik, 'is one of our greatest engineering creations.'"

"True, it begins with a cocoa bean plucked from a tree. But no one would eat a raw cocoa bean. "It tastes revolting," Miodownik says in his new book, Stuff Matters."

"But cut it, leave it, roast it, tinker with it for a couple of centuries (and add sugar) ..."