From Thomas a Kempis' The Imitation of Christ - Book 2, Chapter 7:
"Blessed is the man who knows what it is to love Jesus, and to despise himself for the sake of Jesus. You must give up all other love for His, since He wishes to be loved alone above all.
Love of creatures is deceiving and constantly changing, but the love of Jesus is true and permanent. If you hold on to creatures, you will fall with them; if you hold on to Jesus, you will remain firmly planted forever.
Love Him then Him as a friend. He will not leave you as others do; nor will He permit you to suffer eternal death. Separate yourself a little from everything, then. Cling, therefore to Jesus in life and death; trust yourself to Him alone who can help you when all others fail you.
The nature of Christ's love is such that it will not admit a rival; He wants you for Himself alone. He desires to sit on the throne of your heart as King; which is His right. If you only knew how to free yourself of the love of creatures, how quickly would He come into your heart!"