Answer:
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.
I sleep by day, I fly by night. I have no feathers to aid my flight. What am I?
I am seen in the water. If seen in the sky I am in the rainbow a jay's feather and lapis lazuli.
What begins with T ends with T and has T in it?
So simple, that I can only point. Yet I guide men all over the world.
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.