A closed mind is like a closed book;

Related:

• A closed mind gathers no
  intelligence...
• A closed mouth maintains a
  happy mind...
• A book is like a garden carried in the pocket.
  Chinese...
• zipperhead n.
  [IBM] A person with a closed mind...
• A closed mind doesn't need drugs.
  It is already wasted...
• A deaf ear is the first symptom of a
  closed mind...
• Fellow with closed mind often has open
  mouth...
• My mind is closed so my body
  speaks...
• Where a mind is closed,
  truth cannot enter...