The Four Immeasurable Minds
사무량심

Mahayana bodhisattvas have four kinds of limitless minds to deliver sentient beings from suffering. These four minds of immeasurable concern for others are: metta, karuṇā, muditā and upekkhā.

The immeasurable mind of kindness (metta) is the mind which considers all sentient beings as one's self and wants to bestow joy upon them. The immeasurable mind of compassion (karuṇā) is the mind which wants to save all beings from suffering. The immeasurable mind of joy (muditā) is the mind which wants to help all beings acquire joy and to share this joy as one’s own. The immeasurable mind of equanimity (upekkhā) treats all beings equally and with compassion without distinguishing between friend and enemy. 

Just as a mother would guard her only child
At the risk of her own life
Even so towards all beings
Let him cultivate boundless mind 
Let thoughts of boundless love pervade the whole world
Above, below and across
Without any obstruction
Without any hatred, without any enmity

-Karaniya Metta Sutta (The Discourse on Loving-Kindness) SN 149-150

- excerpt from Buddhist English (Elementary 2) published in 2014 by the Jogye Order of Korean Buddhism​​​