Variety: Matthew 5v8

Blessed are the pure of heart; for they shall see God. —Matthew 5:8  

Cynthia Bourgeault explains how understanding the ancient meaning of the word passion can help us gain emotional equilibrium:   
The tradition from about the 4th century on has been unanimous with what gets in the way of becoming pure of heart. I will quote directly from the Philokalia: “The problem with the passions is that they divide the heart.” The passions are the culprit that sucks the heart out of its capacity to see with equanimity and clarity, with luminosity and radiance, and makes it the slave of your personal drama.    
Nowadays, we think of passion as a good thing, as authenticity, and joie de vivre, the energy of our being coming through. Passion is the capacity to relate to life and get some juice out of it. We keep running this map: that if you can only find what you’re passionate about, you’ll become authentic. I’m not going to say that meaning is wrong, but I will say that that meaning is modern. In ancient texts it has a different meaning: “Passio” is the first-person singular passive of the word which means “I suffer. I am acted upon.” What passion always refers to in the ancient texts is this peculiar, compulsive nature of stuck emotion. The passions are really stuck emotions, revolving around themselves to generate drama.   
There’s a great teaching from the 4th-century spiritual teacher, Evagrius, the first real spiritual psychologist of the Christian West. He did an interesting analysis of how when you’re in a deep field of gathered stillness something will rise up as a thought and quickly become a thought chain. At first it doesn’t have any energy in it but as soon as it hooks onto a sense of myself, as soon as it becomes an “I-story,” it becomes a passion. It’s usually at this point, if you’re not terribly self-aware, that it comes to the surface in the form of rage, anger, hurt or fear, or all of those.   
Once it becomes a passion and it’s stuck to your story, it can do nothing else but churn up more emotion, which then goes down into your physical body and steals your energy of being. Evagrius’ advice is that you have to learn to nip the thought in the bud before it becomes a passion. It’s a kind of wonderful combination of what we might call witnessing presence or practice, developing the capacity to see, combined with kenosis, the willingness to let go of the satisfaction you get from your drama. That is what clears the radar screen.   
The core practice for cleansing and restoring the heart to its organ of spiritual seeing, becomes supremely, in Christianity, the path of kenosis, of letting go. The seeing will come, but the real heart of working with emotion is the willingness to let go, to sacrifice your personal drama, letting go at that level, so that you can begin to see with a pure heart.