The Mercy

Mercy is defined as kindness, affability, benedicence. The beatitudes of Matthew tell us a beatitude concerning mercy: Blessed are the merciful, for they shall be shown mercy. Matthew 5: 7.
The Mercy returns mercy, or expressed in another way: the spiritual gifts return spiritual gifts. The Spiritual gifts are perfections, explains Tomas Aquinas teacher of the scholastic. The beatitudes implicitly tell us about the  law of the return: you  reap what you saw. The right actions bring us blessings.
The Beatitudes carry a concept: happiness, but not happiness as a false good, but as a return, as a collateral effect. When we take the right, the correct actions we diminish, we minimize suffering, and as the opposite of happiness is suffering, when we decrease this last concept we predispose ourselves to happiness.
The minimization of the suffering is an ethical goal to achive happiness.
http://www.quintoevangelio.com.ar/en/articles/item/109-mercy.html

But earnestly desire the greater gifts, 1 Corinthians 12:31

To understand the phrase "But earnestly desire the greater gifts" from 1 Corinthians 12:31, we must understand what means to live according to the spirit (Romans 8:5).
God is the origin of the perfections we observe in the cosmos, to these perfections we call them spiritual gifts.
The gifts are lived because we grow. They are way, that is, we all have a ranking of rectitude, of mercy. 
They are progressive and are linked together, an example of a bond: Blessed are the pure in heart because they will see God, Matthew 5: 8, in this example a gift in this case integrity returns contemplative activity, the law of return acts upon our actions (You reap what your sow), the spiritual gifts return spiritual gifts as in this case. 
The spiritual gifts are progressive because we bear fruits: the fruits of the spirit, Galatians 5:22-23 (love, joy, peace, forbearans, kindness, goodness, faithfulness, gentleness, self control); and the works of the flesh: Galatians 519-21 (wrath, strife, seditions, envyngs, murders, drunkeness, orgies, adultery, fornication, witchcraft, hatred, litigations, jealousy).
Tomas Aqunas makes a distinction between the spiritual gifts of the will: mercy, rectitude, continuous improvement, constancy (fear of the lord); and the spiritual gifts of the understanding: good discernment, wisdom and spiritual gift of knowledge.
The search of wisdom and the progressive thinking lead us to the greater gifts: the eternal life, the perseverance, the fruits of the spirit, and the spiritual gifts of understanding.
http://www.quintoevangelio.com.ar/en/articles/item/104-can-we-do-profecy-and-when-a-profecy-is-good.html