Although not a great deal has been said about heaven in the Christian tradition, it is part of the traditional notion of heaven that the blessed are in a condition of perfect happiness. In this life we can be happy to a certain degree, but mixed with earthly happiness is disappointment, frustration, and even sorrow. In heaven, by contrast, there is no sadness, nothing is lacking, happiness is complete. The usual way of explaining this perfect happiness is in terms of the ‘beatific vision’ – the face to face relationship of knowing and loving God which the blessed enjoy. On earth we experience only finite objects; nothing that we come to know ever completely satisfies our desire to know, and nothing that we love ever completely satisfies our will. But in the beatific vision we shall be in a direct relationship with the infinite God, who in his boundless perfection will completely ‘fill up’ our capacities to know and love. As the completely adequate object of these capacities, God will make us perfectly happy. As Aquinas puts it, ‘…But if God alone were seen, who is the fount and source of all being and of all truth, he would so fill the natural desire for knowledge that nothing else would be desired, and the seer would be completely happy.’
Book Review: Seeing God: The Beatific Vision in Christian Tradition