Answer:
Describes universities like Harvard and can be poisonous.
All about, but cannot be seen, Can be captured, cannot be held, No throat, but can be heard.
This is needed both for courage and hardcover books.
What does everyone know how to open but not how to close?
As soft as silk, as white as milk, as bitter as gall, a thick green wall, and a green coat covers me all.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?