For by teaching, one learns more; and in speaking, one is often a hearer along with his audience. For the teacher of him who speaks and of him who hears is one—who waters both the mind and the word. Thus the Lord did not hinder from doing good while keeping the Sabbath; but allowed us to communicate of those divine mysteries, and of that holy light, to those who are able to receive them. He did not certainly disclose to the many what did not belong to the many; but to the few to whom He knew that they belonged, who were capable of receiving and being moulded according to them. But secret things are entrusted to speech, not to writing, as is the case with God.
Schaff, Philip (2009-06-08). Ante-Nicene Fathers Volume 2 – Enhanced Version (Early Church Fathers) (Kindle Locations 15011-15016). Christian Classics Ethereal Library. Kindle Edition.
Clement of Alexandria
The Stormata, or Miscellanies