Saint Macarius (?-405), monk in Egypt
Spiritual homilies, no.51

I am writing to you, my brothers, so you might know that, since the day when Adam was created until the end of the world, the Evil One wages war against the saints without respite (Rev 13,7)... They are few, however, who realize that this destroyer of souls lives with them inside their bodies, close to the soul. It is there that they feel distress and there is no one on earth to comfort them. That is why they look to heaven and place all their expectation there, waiting to receive something within themselves. And by means of this strength and thanks to this armor of the Spirit (Eph 6,13), they shall overcome. For truly, it is from heaven that they acquire a strength hidden from the eyes of the flesh. So long as they seek God with all their heart, God's strength constantly comes in secret to their assistance... It is precisely because they are sensitive to their weakness and are unable to overcome that they so ardently beg for God's armor and, thus clothed for the fight with the weapons of the Spirit (Eph 6,13), they become victorious...

You should know, then, beloved brethren, that in all those who have prepared their soul to provide good soil for the heavenly sowing, the enemy makes haste to sow his tares... Know also that those who do not seek the Lord with all their heart are not tempted by Satan in so manifest a way; rather, it is in hidden ways and more by trickery that he tries... to push them away from God.

But now, brothers, take heart and don't be afraid of anything. Don't allow yourselves to be frightened by the imaginations stirred up by the enemy. Don't give in to a confused restlessness in prayer by multiplying unnecessary petitions, but receive the Lord's grace with contrition and repentance... Take heart, be comforted, hold fast, concern yourselves with your souls, persevere in prayer with all zeal... For all those who seek God in truth will receive divine strength in their soul and, in receiving this heavenly unction, they will feel within themselves the taste and sweetness of the world to come. May the peace of the Lord, that peace which was with all the holy fathers and kept them safe from every temptation, be also with you.