Gnosticism in relation to literature

[MementoMori]

Could someone please give me an explanation of what the word Gnosticism means when it's used in relation to literature? I've heard someone describe Moby Dick and other books as being "Gnostic" but I have no idea what that means. I know that the Gnostic gospels are the apocryphal texts of the New Testament, but that's as far as my knowledge goes. Wikipedia explains that Gnosticism is

"the thought and practice, especially of various sects of late pre-Christian and early Christian centuries, distinguished by the conviction that matter is evil and that emancipation comes through gnosis (knowledge)."

this quick definition makes sense in the context of Moby Dick, but the page quickly becomes obscure and difficult to follow; apparently there are many different Gnostic movements, each with their own texts, spanning different cultures and religions. It seems more like a way of interpreting religions than a religion in and of itself. Can anyone clarify?

[ralfyman]

There is a definition in bullet points found in the middle of this page:

http://gnosis.org/whatisgnostic.htm

[MementoMori]

Thanks. That's a good starting point.