The enemy is within ourselves. An invisible war is taking place within us. If interior evil is defeated, then the external, weaker, foe will surrender.
A life of spiritual endeavor is the mother of sanctity; from it is born the first experience of perception of the mysteries of Christ--which is called the first stage of spiritual knowledge.
Demons often transform themselves into angels of light and take the form of martyrs, and make it appear to us during sleep that we are in communication with them. Then, when we wake up, they plunge us into unholy joy and conceit. But you can detect their deceit by this very fact. For angels reveal torments, judgments and separations; and when we wake up we find that we are trembling and sad. As soon as we begin to believe the demons in dreams, then they make sport of us when we are awake too. He who believes in dreams is completely inexperienced. 'But he who distrusts all dreams is a wise man. Only believe dreams that warn you of torments and judgments. But if despair afflicts you, then such dreams are also from demons.
It is, indeed, impossible for the mind not to be troubled by thoughts, but accepting them or rejecting them is possible for everyone who makes an effort...therefore we practice the frequent reading of Scripture, so that we may be open to a spiritual point of view. For this reason we frequently chant the psalms, so that we may continually grow in compunction. For this reason we are diligent in vigils, fasting, and praying, so that the mind which has been stretched to its limits may not taste earthly things but contemplate heavenly ones. When these things cease because negligence has crept in again, then, it is inevitable that the mind, by the accumulated filth of the vices, will soon turn in a carnal direction and fall.
First of all it must be understood that it is the duty of all Christians - especially of those whose calling dedicates them to the spiritual life - to strive always and in every way to be united with God, their creator, lover, benefactor, and their supreme good, by whom and for whom they were created. This is because the center and the final purpose of the soul, which God created, must be God Himself alone, and nothing else - God from whom the soul has received its life and its nature, and for whom it must eternally live. For all visible things on earth which are lovable and desirable - riches, glory, wife, children, in a word everything of this world that is beautiful, sweet, and attractive - belong not to the soul but only to the body, and being temporary, will pass away as quickly as a shadow. But the soul, being eternal by its nature, can attain eternal than all beauty, sweetness, and loveliness, and He is its natural home, whence it came and whither it must return. For as the flesh coming from the earth returns to the earth, so the soul coming from God returns to God and dwells in Him. For the soul was created by God in order to dwell in Him forever; therefore in this temporary life we must diligently seek union with God, in order to be accounted worthy to be with Him and in Him eternally in the future life.
Restrain the excitable power of your soul by love; mortify the desiring power by self-mastery; give wings to the thinking power by prayer, and the light of your mind will never be dimmed.
It is impossible for the soul to be liberated from turbulent thoughts without the virtue of non-possessiveness. And without peace of the bodily senses it is impossible for the soul to have a peaceful intellect. And if it does not come into temptations it will not acquire wisdom of the Holy Spirit. And without laborious and persistence in reading, it will not come to the discernment of thoughts. And without the stillness of thoughts, the intellect cannot move to seek the hidden mysteries of God.
Do not be despondent when fighting against the incorporeal enemy, but even in the midst of your afflictions and oppression praise the Lord, Who has found you worthy to suffer for Him, by struggling against the subtlety of the serpent, and to be wounded for Him at every hour; for had you not lived piously, and endeavored to become united to God, the enemy would not have attacked and tormented you.
Do not oppose the thoughts, which the enemy sows in you, but rather cut off all converse with them by prayer to God. We have not always strength enough so to oppose hostile thoughts as to stop them; on the contrary, in such attempts they frequently inflict us with a wound that is long in healing.
We must always pray to the Lord to tell us what to do, and the Lord will not let us go astray. Adam was not wise enough to ask the Lord about the fruit which Eve gave him, and so he lost paradise.
For by prayer we obtain the divine favor, by fasting we extinguish the concupiscences of the flesh, by almsgiving sins are redeemed (Dan. iv. 24); and by all three together, the image of God is renewed in us, provided that we are ever ready in His praise, eager without ceasing for our own purification, and disposed at all times to assist our neighbor.
The day will come when you are toiling at self-observation and self-constraint, and the adversary will come up and mumble in your ear, 'This will all happen eventually. You’ve been working hard, now take it easy a little bit!' This is such a tempting suggestion that it does not immediately occur to you that you should counter it, or that it is so bad that however little you give in to it, it will cause such inner disturbance. Indulging yourself is just like a tiny hole in a dam. Once a hole has formed, the dam cannot hold; the water will inevitably destroy it. Indulgence does the same thing inside of us; everything will be dispersed, so it will be necessary to start all over again to restore ourselves. Fear this as your most evil enemy, although he speaks with the sweetest words.
Many are the obstacles that stand in the way of pleasing God; for not merely poverty and obscurity but also riches and honor are trials for the soul. Indeed, to some extent even the solace and ease which grace bestows on the soul can easily become a temptation and a hindrance if the soul is not properly conscious of these effects of grace and does not enjoy them with great circumspection and understanding: for the spirit of evil tries to persuade the soul to relax now it possesses grace, and so contrives to implant in it sluggishness and apathy.