Emotional intelligence is defined as a person’s ability to identify emotions (in both themselves and others), to recognize the powerful effects of those emotions, and to use that information to inform and guide behavior. Ever since Daniel Goleman’s international best-seller Emotional Intelligence was released in 1995, interest in the quality has risen dramatically.

The terms emotional intelligence (EI) and emotional quotient (EQ) may be new, but the concepts definitely aren’t.

[My new book, EQ, Applied, is a practical approach that illustrates just how EQ works–and doesn’t work–in the real world.]

In fact, writers and thinkers from various backgrounds have explored this concept through the years. Here are 23 of my favorite quotes about emotions and learning to deal with them:

1. “I don’t want to be at the mercy of my emotions. I want to use them, to enjoy them, and to dominate them.”
–Oscar Wilde

2. “One ought to hold on to one’s heart; for if one lets it go, one soon loses control of the head too.”
–Friedrich Nietzsche

3. “I’ve learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel.” —(probably not) Maya Angelou

4. “Few people are capable of expressing with equanimity opinions which differ from the prejudices of their social environment. Most people are even incapable of forming such opinions.”
–Albert Einstein

5. “Emotion can be the enemy, if you give into your emotion, you lose yourself. You must be at one with your emotions, because the body always follows the mind.”
–Bruce Lee

6. “The idea that you have to be protected from any kind of uncomfortable emotion is what I absolutely do not subscribe to.”
–John Cleese

7. “Feelings can’t be ignored, no matter how unjust or ungrateful they seem.”
–Anne Frank

8. “Tact is the knack of making a point without making an enemy.”
–Isaac Newton

9. “Everyone must be quick to listen, slow to speak, slow to anger…”
–The Bible (James 1:19)

10. “When a man is prey to his emotions, he is not his own master.”
–Baruch Spinoza

11. “Your emotions are the slaves to your thoughts, and you are the slave to your emotions.”
–Elizabeth Gilbert

12. “Feelings are something you have; not something you are.”
–Shannon L. Alder

13. “Your heart will always go where your mind wanders.”
–Shannon L. Alder

14. “People who keep stiff upper lips find that it’s damn hard to smile.”
–Judith Guest

15. “How you react emotionally is a choice in any situation.”
–Judith Orloff

16. “The emotions of man are stirred more quickly than man’s intelligence.”
–Oscar Wilde

17. “It is both a blessing and a curse to feel everything so very deeply.”
–David Jones

18. “Tears are a form of communication – like speech – and require a listener.”
–Erica Jong

19. “Our emotional response is driven by the proximity of events.”
–Piyush Shrivastava

20. “Emotions are not problems to be solved. They are signals to be interpreted.”
–Vironika Tugaleva

21. “Anger is a legitimate feeling, one often designed for self-protection.”
–Kimberlee Roth

22. “Some prisons don’t require bars to keep people locked inside. All it takes is their perception that they belong there.”
–Lysa TerKeurst

23. “One half of me is a hopeless romantic. The other half is well… just realistic.”
–Faraaz Kazi

Enjoy this post? Check out my book, EQ Applied, which uses fascinating research and compelling stories to illustrate what emotional intelligence looks like in real life. 

A version of this article originally appeared on Inc.com.