For cleanness of the eye disposes one to see clearly: hence the clean of heart are promised that they shall see God. Again, to make peace either in oneself or among others, shows a man to be a follower of God, Who is the God of unity and peace.
 Thomas Aquinas, Summa Theologica (1274). copy citation

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Author Thomas Aquinas
Source Summa Theologica
Topic unity peace
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/17897/pg17897-images.html

Context

“Hence Our Lord promised the merciful that they should obtain mercy, and be delivered from all misery.
The last two beatitudes belong to contemplative happiness or beatitude: hence the rewards are assigned in correspondence with the dispositions included in the merit. For cleanness of the eye disposes one to see clearly: hence the clean of heart are promised that they shall see God. Again, to make peace either in oneself or among others, shows a man to be a follower of God, Who is the God of unity and peace. Hence, as a reward, he is promised the glory of the Divine sonship, consisting in perfect union with God through consummate wisdom.
Reply Obj. 1: As Chrysostom says (Hom. xv in Matth.) , all these rewards are one in reality, viz. eternal happiness, which the human intellect cannot grasp.” source