If we do not purify and strip the heart of everything earthly, the love of God cannot enter in and possess it all. Detach thy heart from all created things, says St. Teresa, and seek God, and thou shalt find Him.
In order to attain to loving God with all our heart, we must separate it from everything that is not God, that does not tend towards God. He chooses to be alone in the possession of our hearts; He admits no companions there; and with reason, because He is our only Lord, Who has given us everything. Still further, He is our only Lover, Who has loved us not for His own interest, but solely from His goodness; and because He thus exceedingly loves us, He desires that we should love Him with all our hearts: Thou shalt love the Lord thy God with all thy heart.
To love God with our whole heart implies two things: the first is, to drive from it every affection that is not for God, or not according to the will of God. “If I knew,” said St. Francis de Sales, “that I had one fibre in my heart that did not belong to God, I would instantly tear it out.” The second is prayer, by which holy love introduces itself into the heart. But if the heart does not fly from the earth, love cannot enter, for it finds no place for itself. On the other hand, a heart detached from all creatures instantly becomes inflamed, and increases in Divine love at every breathing of grace.
“Pure love,” said the holy Bishop of Geneva, “consumes everything that is not God, in order to change it into itself; because everything that is done for God is the love of God.” Oh, how full of goodness and liberality is God to those souls that seek nothing but Him and His will! The Lord is good to them that seek him. (Lam. iii. 25). Happy he who, living still in the world, can say from his heart with St. Francis: “My God and my All!” and thus hold in contempt all the vanities of the world. “I have despised the kingdoms of the world, and all the glory of this life, for the love of Jesus Christ my Lord.”
When, then, creatures would enter our heart and take a share of this love, all of which we owe to God, we must immediately banish them, shutting the door against them, and saying: “Begone! Begone to those who desire you; my heart I have given wholly to Jesus Christ; for you there is no place.” And, in addition to this resolution to desire nothing but God, we must hate that which the world loves, and love that which the world hates.
O Jesus, I do not desire that creatures should have any part in my heart. Thou must be my only Lord by possessing it altogether. Let others seek the delights and grandeurs of the world. Thou alone in this life and in the next must be my only portion, my only Good, my only Love. O Mary, thy prayers can make me belong wholly to Jesus.
Above all, to attain to perfect love, we must deny ourselves, embracing that which is distasteful to self-love, and rejecting that which self-love demands. A certain thing is pleasant to us; for that very reason we must reject it. A certain medicine is disagreeable, because it is bitter. We must take it for the very reason that it is bitter. It is unpleasant to us to do good to a certain person who has been ungrateful to us; we must, by all means, do him good, for the very reason that he has been ungrateful.
Further, St. Francis de Sales said that we must love even virtues with a detachment of heart; for example, we ought to love meditation and retirement; but when they are forbidden to us, through the calls of obedience or of charity, we must leave both the one and the other without being disquieted. And thus it is necessary to embrace with equanimity everything that happens to us through the will of God. Happy is he who wishes to have, or refuses to have, whatever happens because God wishes it or refuses it, without inclining to either side. And therefore we must pray the Lord to enable us to find peace in everything that He appoints for us.
It is certain that no one lives more happy in the world, than he who despises the things of the world, and lives in continual conformity to the will of God. Therefore, it is a useful thing frequently during the day, or at least at the times of prayer and Communion, to renew at the foot of the Crucifix the total renunciation of ourselves and of all our possessions, saying: O my Jesus, I desire to think no more of myself; I give myself wholly to Thee, do with me what Thou wilt. I see that everything that the world offers me is vanity and deceit. From this day, I would seek nothing but Thee, and Thy good will; help me to be faithful to Thee. O Virgin Mary, pray to Jesus for me.
(Monday Meditation in Holy Week – by St Alphonsus Liguori)