The term "labyrinth" is often used interchangeably with "maze" in English. Many current historians and fans see a distinction between the two due to the lengthy history of unicursal portrayal of the legendary labyrinth. However, both terms have been used extensively since their first appearances in European literature. The ancient Greek writer Diodorus Siculus used the words "αρτηρινή" (artemision) or "χείλαβος" (cheilos)" to describe the maze as we know it today. The Latin word "labyrinthus" was also used by the authors of classical texts to describe the same thing. In fact, the modern English word "labyrinth" is derived from Latin via Greek. In medieval Europe, the word "maze" came to be used instead. This may be because the unicursal design of the maze was not introduced into Europe until much later. However, the term "labyrinth" remained in use among writers and poets. For example, John Milton used the words interchangeably in his 1667 poem Paradise Lost. Today, the two terms are used almost interchangeably to describe any maze-like structure. The only real difference between them is that a labyrinth must contain a center point to be considered a true labyrinth.