What is apocalyptic literature anyway?

Scholars like to toss around big words to sound smart. Bible scholars' favorite big words are things like "eschatological," "intertextuality," and "apocalyptic literature." I've read a lot of things that talk about apocalyptic literature, but few that sit down and try to really define it. But today I was lucky and I found two different definitions of "apocalyptic literature" in two different places. I thought I'd pass them along to you.

1. Apocalyptic literature is defined as "symbolic, visionary, prophetic literature, usually composed during oppressive conditions and being chiefly eschatological in theological content." (NIV Study Bible - 2002)

2. "Apocalypse" is a genre of revolutionary literature with a narrative framework, in which a revelation is mediated by an otherworldly being to a human recipient, disclosing a transcendent reality which is both temporal, insofar as it envisages eschatological salvation, and spatial insofar as it involves another, supernatural world." (John J. Collins quoted in New Interpreters Bible, vol. VII, p.22)

I'm not sure whether I agree with the idea of genre-definition in general (having a post-modern streak in me) let alone with the above definitions. I'm not quite sure I even understand Collins' definition. (I'm still having a hard time figuring out how a transcendent reality can envisage something.) But here are the definitions for your enjoyment and perusal.