Psalm 118:16 On Thy statutes will I meditate; I will not forget Thy words.
St. Basil the Great bears witness that in his time children were made to memorize some psalms and parables. Do we do anything like that now? Is anything like that done by those who have taken up the yoke of asceticism? Yes, in many ways we have fallen behind the salutary practices of old. This, however, does not diminish the value of what is described in this verse. It means the following: Memorize verses of Scripture considered in the preceding text, and repeat what was memorized whenever the mind and speech are free. The Hebrew word corresponding to will meditate means “to turn over with delight in the mind and on the tongue” — as one might a piece of candy, for instance. Such an occupation could be offered to all who sincerely seek to please God in all.
Among us, amy of those living ascetic lives read the Psalter at home in their cells. This partly fulfills the lesson of our verse. And perhaps home prayers, personal and monastic, could be regarded as this type of activity. But more directly it means: to intentionally choose passages of the Holy Scriptures for memorizing and then repeating them in our minds.
Through this last practice, the commandments, having already occupied all the faculties of the soul, shall occupy the memory and sanctify it. The blessing from this is indescribable! …The same thing happens to the soul as to poor fruit when it is sugared. The sugar penetrates its pores, making it sweeter and protecting it from spoiling. Similarly the soul, saturated with memorized words of God, rejects the corruption of shameless and empty thoughts and is filled to sweetness with the memory of things divine.
…If we accept this, then here is a rule for beginners as to how to deal with evil thoughts. Memorize as many passages of the Scriptures as possible, in particular the words of and deeds of Christ the Savior, and repeat them often. (Psalm 118, A Commentary by St. Theophan the Recluse, pp. 47-48)