On Divine Meditation:

In ancient times very many monks fell into fatal heresy soley because they allowed themselves to investigate dogmas beyond their powers of comprehension. 'A humble monk,' Climacus again teaches, 'will not meddle with mysteries, but a proud one will pry into the divine judgements.' Very True! In one who is immature and unfit for it the desire to undertake divine meditation is suggestion of conceit, is a proud and imprudent desire. Excercise yourself in prayer and in soul building reading, and this exercise will be an exercise in divine meditation that is right, safe and pleasing to God.

Bishop Ignatius, The Arena, Chapter 27