From The Last Byzantine Renaissance, by Steven Runciman, 1970:
'...what the later Greeks had to say in general was restricted by their distinction between the Inner and the Outer learning.
'The Inner learning dealt with eternity, with truths that had existed before the beginning of time; and man could only know what God in his goodness had chosen to reveal. The rest was unknown and unknowable.
'The student of the Inner Learning might be able to expound and explain these revealed truths, but he could not add to them unless the Holy Spirit vouchsafed further revelations.
'The mystic might be permitted to penetrate a little further into the unknown but his experience was not an intellectual exercise. (...)
'The sophists who arrogantly explained the universe in terms intelligible to the intellect had no place in Byzantium.
'Philosophy could not open the door to Inner Learning.'