I have to disagree with the thought-form ideas posited in this thread. Although I believe in egregores and similar concepts, we must not lose sight of one very important basic element: the Mythos is a virtually endless system because Lovecraft has given his readers many hidden hints about what else is out there beyond his primary dreamed-up Gods and creatures. Would even all of mankind combined have the will-power to call to life even a fraction of this mythos? I think not.

But, interesting question: if it would be able to conceive of, for example, Cthulhu, would Cthulhu's abilities and knowledge be limited to what we have injected him with? Or would he take all the information and veiled hints that Lovecraft has written about him and that we don't know about (e.g. "I learned whence Cthulhu first came, and why half the great temporary stars of history had flared forth. I guessed [...] the secret behind the Magellanic Clouds and globular nebulae...") and be able to further develop himself and take that hidden, abstract information and develop those as well?