Here is one of my favorite quotes from C. S. Lewis:
When I have learnt to love God better than my earthly dearest, I shall love my earthly dearest better than I do now.
Insofar as I learn to love my earthly dearest at the expense of God and instead of God, I shall be moving towards the state in which I shall not love my earthly dearest at all.
When first things are put first, second things are not suppressed but increased.
This has echoes of Augustine’s Confessions (XI.29):
He loves Thee too little, who loves anything together with Thee, which he loves not for Thy sake.
Writing to Dom Bede (April 16, 1940), Lewis mentioned a great line he spotted from Denis de Rougemont’s Passion and Society about sensual love: “It ceases to be a devil when it ceases to be a god.”
Lewis comments,
Isn’t that well put? So many things—nay every real thing—is good if only it will be humble and ordinate.
