This is from a famous H. P. Lovecraft quote (which was also used by metal groups Iron Maiden (on the Live After Death album cover) and Metallica (in the song ‘The Thing That Should Not Be’)):
That is not dead which can eternal lie
And with strange aeons even death may die
It is supposed to be a quote from Abdul al-Hazred’s Necronomicon, and Lovecraft uses the verse in several stories, particularly in The Call of Cthulhu and The Nameless City.
In reality, I’m told the quote originated with the Victorian decadent poet Algernon Charles Swinburne, but I have no definite reference on this.