Today is the feast of St. Alphonsus Liguori, Doctor of the Church. From his Practice of the Love of Jesus (chapter 12):
The primary object of Christian hope is God, whom the soul enjoys in the kingdom of heaven. But we must not suppose that the hope of enjoying God in Paradise is any obstacle to charity; since the hope of Paradise is inseparably connected with charity, which there receives its full and complete perfection. Charity is that infinite treasure, spoken of by the Wise Man, which makes us the friends of God: An infinite treasure, which they that use become the friends of God. The angelic Doctor St. Thomas says, that friendship is founded on the mutual communication of goods; for as friendship is nothing more than a mutual love between friends, it follows that there must be a reciprocal interchange of the good which each possesses. Hence the saint says, "If there be no communication, there is no friendship."