"Of Miracles" is the tenth section of David Hume's An Enquiry Concerning Human Understanding (1748). In this piece, Hume states that evidence of miracles is never sufficient for rational belief.

"Extraordinary claims require extraordinary evidence", also known as the Sagan standard, is an aphorism popularized by science communicator Carl Sagan. He used the phrase in his 1979 book Broca's Brain and the 1980 television program Cosmos. It has been described as fundamental to the scientific method and is regarded as encapsulating the basic principles of scientific skepticism.