“ The man who never alters his opinion is like standing water, and breeds reptiles of the mind. ”
Source: The Marriage of Heaven and Hell
Similar Quotes
When a man gives his opinion, he's a man. When a woman gives her opinion, she's a bitch. 
Since you alone are responsible for what goes on in your mind, only you can change your thoughts. 
We are addicted to our thoughts. We cannot change anything if we cannot change our thinking. 
Your opinions are a wall, not only for others but also for yourself. A closed mind means closed possibilities