Some of Lovecraft's work was inspired by his own nightmares.His interest started from his childhood days when his grandfather would tell him Gothic horror stories.Lovecraft's materialist views led him to espouse his philosophical views through his fiction; these philosophical views came to be called cosmicism. Cosmicism took on a more pessimistic tone with his creation of what is now known as the Cthulhu Mythos; a fictional universe that contains alien deities and horrors. In his letters, Lovecraft jokingly called his fictional mythology "Yog-Sothothery.