Reading spiritual books is essential as this is how we feed the soul. If one diminishes the amount of garbage one reads that the world vomits up, and in turn increases time spent reading scriptures, spiritual books, lives of the saints and patristics, ones spiritual health increases. The great saint and mystic of the Western Church of recent times said:
“Don’t consider me too demanding if I ask you once again to set great store by holy books and read them as much as you can. This spiritual reading is as necessary to you as the air you breathe.”
The perfect lead-up to the next precepts is found in another quote from Padre Pio: "Through the study of books one seeks God; by meditation one finds him."
““Moreover, if the Devil does not dare to enter into the house where the Gospel lies, much less will he ever seize upon the soul which contains such thoughts as these, and no evil spirit will approach it, nor will the nature of sin come near. Well, then, sanctify your soul, sanctify your body by having these thoughts always in your heart and on your tongue. For if foul language is defiling and evokes evil spirits, it is evident that spiritual reading sanctifies the reader and attracts the grace of the Spirit.” St. John Chrysostom
See --St. Ignatius Brianchaninov Arena chapter 9