According to Lovecraft, humans can never fully understand Cthulhu because his very existence is beyond mortal comprehension. Lovecraft's universe contains many creatures that are equally incomprehensible. Some of these are known as the Great Old Ones, or the Old Ones, and are powerful, ageless beings from beyond the stars. Though Lovecraft used the phrase "the Great Old Ones" in contradictory ways, most of his fans accept that Cthulhu is one of these extraterrestrial beings that only partially exist in our dimension.
Some of the Old Ones have massive, cosmic physical forms that dwarf celestial bodies while others have little to no physical presence in our world at all. Lovecraft refers to Cthulhu as the Priest of the Old Ones, though whether he means that Cthulhu led others to worship the Old Ones or was the head of the religion for the Old Ones themselves is not clear.
Because Lovecraft's stories are almost always first-person accounts from a narrator with limited knowledge, we can only know as much as the storytellers tell us. Other authors have expanded Lovecraft's universe, and fans across the world engage in long debates over which works are canon in the mythology and which should be ignored. What we do know is that the Great Old Ones came from distant planets light years away from Earth, and that they may actually exist -- at least partially exist -- in dimensions unperceivable by human beings.
Several of the Great Old Ones came to Earth while the planet itself was still very young, though not uninhabited. At that time, a race of beings called the Elder Things -- which, confusingly, Lovecraft sometimes also called the Old Ones -- had colonized the planet, creating huge cities and possibly even creating the first life on Earth. The Great Old Ones waged war on the Elder Things, eventually leading to an uneasy truce. The Great Old Ones settled in the stone city of R'lyeh. They ruled the Earth for millions of years and were around when the first humans evolved.
In those prehistoric days, Cthulhu communicated with humans telepathically, and led them to ancient temples and sites where the humans found statues and artwork from other worlds. The Great Old Ones made the statues from materials that don't exist on our planet. Cults worshipping Cthulhu and the other ageless beings began to form.
Not long after the appearance of man, R'lyeh sank beneath the ocean, trapping the Old Ones inside. Small sections of mankind remembered the telepathic communications with Cthulhu and continued to worship him. Lovecraft writes of cults spread across the globe, from China to Greenland to the swamps of Louisiana. These cults repeat the alien chant, "ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn!" Try saying that three times fast -- or at all, in fact.
Lovecraft explains that thought cannot penetrate the deep waters of the ocean, and so the Great Old Ones are left isolated from mankind, unable to influence them directly. They lay dormant in the city, awaiting the day when the stars will align and R'lyeh will break the ocean's surface once more. Lovecraft even gives the coordinates for R'lyeh in his story "The Call of Cthulhu." You would find the city at S 47° 9', W 126° 43' 47". Even the city's architecture is beyond the grasp of human understanding -- Lovecraft describes it as non-Euclidian, filled with strange angles and odd curved surfaces that seem concave one moment and convex the next.
In the next section, we'll look at some of Lovecraft's other creations in his mythology known as the Cthulhu mythos.