Constantly mentioned here, can someone please give us some information/resources/books/links etc on meditation?

Couple questions:
What can u do with it?
What's the purpose?
How can it benifit my LD quest?



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Come to think of it, how many different world of altered state pseudo newage powerment mind control psycho mediattive control worlds are there LOL? (Besides LD, OBEs, meditation, etc)