In this life no one can fulfill his longing, nor can any creature satisfy man's desire. Only God satisfies; he infinitely exceeds all other pleasures. That is why man can rest in nothing but God. As Augustine says, "You have made us for yourself, O Lord, and our heart can find no rest until it rests in you."
Eternal life consists of the joyous community of all the blessed, a community of supreme delight, since everyone will share all that is good with all the blessed. Everyone will love everyone else as himself, and therefore will rejoice in another's good as in his own. The happiness and joy of each grows in proportion to the joy of all.
-- St. Thomas Aquinas