In the Middle Ages, people used seals to protect important communications from forgery, acting like a signature. Everyone from individuals to organizations had their own unique seal.

Yet it was frequently discussed in a language that is more resonant of the Middle Ages than the scientific laboratory.

Detail from a 10th century religious book is seen displayed at the library at Salisbury Cathedral in England. (Matt Cardy/Getty Images) Most Americans get their ideas about the Middle Ages from ...

In the Middle Ages, people used seals to protect important communications from forgery, acting like a signature. Everyone from individuals to organizations had their own unique seal.

Cats had a bad reputation in the middle ages. Their presumed links with paganism and witchcraft meant they were often treated with suspicion. But despite their association with the supernatural ...