From On the Holy Spirit (1.2) by St. Basil the Great:
To count the terms used in theology as of primary importance, and to endeavour to trace out the hidden meaning in every phrase and in every syllable, is a characteristic wanting in those who are idle in the pursuit of true religion, but distinguishing all who get knowledge of "the mark" "of our calling;" for what is set before us is, so far as is possible with human nature, to be made like God. Now without knowledge there can be no making like; and knowledge is not got without lessons. The beginning of teaching is speech, and syllables and words are parts of speech. It follows then that to investigate syllables is not to shoot wide of the mark, nor, because the questions raised are what might seem to some insignificant, are they on that account to be held unworthy of heed. Truth is always a quarry hard to hunt, and therefore we must look everywhere for its tracks. The acquisition of true religion is just like that of crafts; both grow bit by bit; apprentices must despise nothing. If a man despise the first elements as small and insignificant, he will never reach the perfection of wisdom.
From The First Theological Oration (section 3) of St. Gregory of Nazianzen:
Not to every one, my friends, does it belong to philosophize about God; not to every one; the Subject is not so cheap and low; and I will add, not before every audience, nor at all times, nor on all points; but on certain occasions, and before certain persons, and within certain limits.
Not to all men, because it is permitted only to those who have been examined, and are passed masters in meditation, and who have been previously purified in soul and body, or at the very least are being purified. For the impure to touch the pure is, we may safely say, not safe, just as it is unsafe to fix weak eyes upon the sun's rays. And what is the permitted occasion? It is when we are free from all external defilement or disturbance, and when that which rules within us is not confused with vexatious or erring images; like persons mixing up good writing with bad, or filth with the sweet odours of ointments. For it is necessary to be truly at leisure to know God; and when we can get a convenient season, to discern the straight road of the things divine. And who are the permitted persons? They to whom the subject is of real concern, and not they who make it a matter of pleasant gossip, like any other thing, after the races, or the theatre, or a concert, or a dinner, or still lower employments. To such men as these, idle jests and pretty contradictions about these subjects are a part of their amusement.