"The ultimate basis of happiness lies in the vision"

“NOW, the end of our desires is God; hence, the act whereby we are primarily joined to Him is basically and substantially our happiness. But we are primarily united with God by an act of understanding; and therefore, the very seeing of God, which is an act of the intellect, is substantially and basically our happiness. However, since this action is most perfect and most appropriate to its object, it is therefore followed by the greatest enjoyment, which adorns and perfects this operation, as beauty does youth, to quote the Ethics (X, 4). As a result, this joy which belongs to the will is a formal complement of happiness. Thus, the ultimate basis of happiness lies in the vision, while its complement consists in the fruition.”

~St. Thomas Aquinas: from Quodlibetal Questions, VIII, 9, 19. (c. Trans. V.J. Bourke)