Meme

A meme was an idea which was transmitted between people. (AUDIO: Rule of the Eminence)

Susan referred to the Library of Alexandria as being a "farm for memes" before remembering that memes were a concept from after Ian and Barbara's time. (AUDIO: The Library of Alexandria)

Behind the scenes

 * While the word "meme" in modern vernacular usually refers to videos or images which are rapidly copied and spread on the internet, it is scientifically used to refer to cultural elements which are spread by a non-genetic means.
 * The word was modelled on the word "gene" and was coined by Richard Dawkins in his 1976 book.