If the first wearable pair of eyeglasses — i.e., the handheld type that one holds on the bridge of the nose — were invented in the 13th century in Italy, when do you think “legs” were invented? Legs are the portion that fit over the wearer’s ears.
Answer below the break:
As hard as it is to believe in hindsight, the legs were not invented until 1727 by British optician Edward Scarlett. A good example of how some of the simplest inventions are non-obvious.