Answer:
A large oasis in the desert. Come with cash and leave with none.
I have no voice but I can teach you all there is to know. I have spines and hinges but I am not a door. Once I've told you all, I cannot tell you more. What am I?
You use a knife to slice my head and weep beside me when I am dead.
I am a pretty one, fluttering in the pale blue sky. Delicate, fragile on the wing, indeed I am a pretty thing. What am I?
I build up castles. I tear down mountains. I make some men blind, I help others to see. What am I?
Before I grow I'm small. When I'm old I grow tall. When I die I give a mighty fall.