This passage is taken from chapter 48 of book three in The Imitation of Christ.
O most happy mansion of the city above! O most bright day of eternity, which night does not darken, but which the highest truth ever enlightens! O day, ever joyful and ever secure, which never changes its state to the opposite! Oh, that this day shine forth, that all these temporal things come to an end! It envelops the saints all resplendent with heavenly brightness, but it appears far off as through a glass to us wanderers on the earth. The citizens of heaven know how joyful that day is, but the exiled sons of Eve mourn that this one is bitter and tedious.
The days of this life are short and evil, full of grief and distress. Here man is defiled by many sins, ensnared in many passions, enslaved by many fears, and burdened with many cares. He is distracted by many curiosities and entangled in many vanities, surrounded by many errors and worn by many labors, oppressed by temptations, weakened by pleasures, and tortured by want.
Oh, when will these evils end? When shall I be freed from the miserable slavery of vice? When, Lord, shall I think of You alone? When shall I fully rejoice in You? When shall I be without hindrance, in true liberty, free from every grievance of mind and body? When will there be solid peace, undisturbed and secure, inward peace and outward peace, peace secured on every side? O good Jesus, when shall I stand to gaze upon You? When shall I contemplate the glory of Your kingdom? When will You be all in all to me? Oh, when shall I be with You in that kingdom of Yours, which You have prepared for Your beloved from all eternity?
I am left poor and exiled in a hostile land, where every day sees wars and very great misfortunes. Console my banishment, assuage my sorrow. My whole desire is for You. Whatever solace this world offers is a burden to me. I desire to enjoy You intimately, but I cannot attain to it. I wish to cling fast to heavenly things, but temporal affairs and unmortified passions bear me down. I wish in mind to be above all things, but I am forced by the flesh to be unwillingly subject to them. Thus, I fight with myself, unhappy that I am, and am become a burden to myself, while my spirit seeks to rise upward and my flesh to sink downward. Oh, what inward suffering I undergo when I consider heavenly things; when I pray, a multitude of carnal thoughts rush upon me!
O my God, do not remove Yourself far from me, and depart not in anger from Your servant. Dart forth Your lightning and disperse them; send forth Your arrows and let the phantoms of the enemy be put to flight. Draw my senses toward You and make me forget all worldly things. Grant me the grace to cast away quickly all vicious imaginings and to scorn them. Aid me, O heavenly Truth, that no vanity may move me. Come, heavenly Sweetness, and let all impurity fly from before Your face.
Pardon me also, and deal mercifully with me, as often as I think of anything besides You in prayer. For I confess truly that I am accustomed to be very much distracted. Very often I am not where bodily I stand or sit; rather, I am where my thoughts carry me. Where my thoughts are, there am I; and frequently my thoughts are where my love is. That which naturally delights, or is by habit pleasing, comes to me quickly. Hence You Who are Truth itself, have plainly said: "For where your treasure is, there is your heart also." If I love heaven, I think willingly of heavenly things. If I love the world, I rejoice at the happiness of the world and grieve at its troubles. If I love the flesh, I often imagine things that are carnal. If I love the spirit, I delight in thinking of spiritual matters. For whatever I love, I am willing to speak and hear about.
Blessed is the man who for Your sake, O Lord, dismisses all creatures, does violence to nature, crucifies the desires of the flesh in fervor of spirit, so that with serene conscience he can offer You a pure prayer and, having excluded all earthly things inwardly and outwardly, becomes worthy to enter into the heavenly choirs.