By St. Theophan the Recluse
Part 1 of 2
A Christian intellectual development occurs when all the truths of the Faith are impressed so deeply into the intellect that the intellect's whole existence is made up of these truths alone. When it begins to reason over something, it reasons according to what it knows of the Christian truths, and would never make the slightest move without them. The Apostle calls this keeping the image of a sound mind (II Tim. 1:7).
Exercises or work related to this are: reading and hearing the Word of God, patristic literature, Lives of the Holy Fathers, mutual discourse and asking questions of those more experienced.
It is good to read or listen, better to have a mutual discourse, and even better to ask questions of those more experienced.
The most fruit-bearing is the Word of God, then patristic literature and the Lives of saints. Incidentally, it is needful to know that the Lives of saints are better for beginners, patristic literature for the intermediate, and the Word of God for the perfect.
All of these are the sources of Truth as well as the means for drawing from them; obviously, impressing them in the mind along with preserving the spirit of zeal also help.
Often one text will warm the spirit for more than a day. There are Lives of which the mere remembrance is enough to inflame zeal. There are also passages in patristic writings that inspire. Therefore we have this good rule: write down such passages and save them, in case you need them later to warm your spirit.
Often neither internal nor external work helps-the spirit remains sleepy. Hasten to read something from somewhere. If this does not help, run to someone to discuss it. The latter performed with faith is rarely fruitless.
There are two kinds of reading: one-ordinary, almost mechanical, and another-discriminating, according to spiritual need and advice. But the first kind is also not useless. It is, as we have said already, what is simply repeated and not studied.
It is most necessary for everyone to have someone with whom he can discuss spiritual matters-someone who already knows all our problems and to whom we can boldly reveal everything on our soul. It is best if it is only one person; two is too many. Idle conversations carried on only in order to pass the time should be avoided at all cost.
Here is a rule for reading:
Before reading you should empty your soul of everything. 
Arouse the desire to know about what is being read.
Turn prayerfully to God.
Follow what you are reading with attention and place everything in your open heart.
If something did not reach the heart, stay with it until it reaches.
You should of course read quite slowly.
Stop reading when the soul no longer wants to nourish itself with reading. That means it is full. If the soul finds one passage utterly stunning, stop there and read no more.
The best time for reading the Word of God is in the morning, Lives of saints after the mid-day meal, and Holy Fathers before going to sleep. Thus you can take up a little bit each day.
During such occupations, you should continually keeping mind the main goal—impressing the truth on yourself and awakening the spirit. If reading or discourse does not bring this about, then they are but idle itchings of the tongue and ears, or empty discussion. If it is done with intelligence, then the truths impress themselves and rouse the spirit, and one thing aids the other. But if the reading or discourse digresses from the proper image, then there is neither one nor the other—truth is stuffed into the head like sand, and the spirit becomes cold and hard smokes over and puffs up.
Impressing the spirit is not the same as searching for it. This requires only that you clarify what the truth is, and hold it in your mind until they bond together. Let there be no deductions or limitations—only the face of truth.
The easiest method for this could lawfully be considered the following: the whole truth is in the catechesis. Every morning take the truth from it and clarify it to yourself, carry it in your mind and nourish yourself with it for as long as it feeds the soul—a day, two days or longer. Do the same thing with another truth, and continue thus to the end. This is a method that is easy and applicable to everyone. Those who do not know how to read may ask for one truth and proceed from there.
We can see that the rule for everyone is this: impress the in Holy little truth in a way that will awaken you. The methods for fulfilling this rule vary, and it is not at all possible to prescribe the same one for everyone.
Thus, reading, listening and discourse that do not impress the truth or awaken the spirit should be considered wrong, as they lead away from the truth. It is a sickness to read many books out of curiosity alone, when only the mind follows what is being read, without leading it to the heart or delighting in its flavor.
This is the science of dreaming; it is not creative, does not hasten success, but is devastating and always leads to arrogance. All your work should be limited, as we have said, to the following: clarify the truth and hold it in the mind until the heart tastes of it. The Holy Fathers put it simply: remember it, hold it in the mind, and have it always before your eyes.