A closed mind is like a closed book; just a block of wood

Rotten wood cannot be carved

A man's faults all conform to his type of mind. Observe his faults and you may know his virtues.

If you wish to know the mind of a man, listen to his words.

The broad-minded see the truth in different religions; the narrow-minded see only the differences

A vacant mind is open to all suggestions, as a hollow mountain returns all sounds