Charity is a virtue which, when our affections are perfectly ordered, unites us to God, for by it we love Him.
 Thomas Aquinas, Summa Theologica (1274). copy citation

add
Author Thomas Aquinas
Source Summa Theologica
Topic virtue love
Date 1274
Language English
Reference
Note Translated by Fathers of the English Dominican Province
Weblink http://www.gutenberg.org/cache/epub/18755/pg18755-images.html

Context

“But charity is not an accidental habit, since it is a more excellent thing than the soul itself: whereas no accident is more excellent than its subject. Therefore charity is not a virtue. On the contrary, Augustine says (De Moribus Eccl. xi) : "Charity is a virtue which, when our affections are perfectly ordered, unites us to God, for by it we love Him." I answer that, Human acts are good according as they are regulated by their due rule and measure. Wherefore human virtue which is the principle of all man's good acts consists in following the rule of human acts, which is twofold, as stated above” source