The heaven is tempered with glacial waters, lest it should be set on fire.

The inferior heaven is called the firmament, because it separates the superincumbent waters from the waters below.
The firmamental waters are lower than the spiritual heaven, higher than all corporeal beings, reserved, some say, for a second deluge; others, more truly, to temper the fire of the fixed stars." Was it for this preposterous scheme--this product of ignorance and audacity--that the works of the Greek philosophers were to be given up?
It was none too soon that the great critics who appeared at the Reformation, by comparing the works of these writers with one another, brought them to their proper level, and taught us to look upon them all with contempt.
Of this presumptuous system, the strangest part was its logic, the nature of its proofs.

It relied upon miracle-evidence.

A fact was supposed to be demonstrated by an astounding illustration of something else! An Arabian writer, referring to this, says: "If a conjurer should say to me, 'Three are more than ten, and in proof of it I will change this stick into a serpent,' I might be surprised at his legerdemain, but I certainly should not admit his assertion." Yet, for more than a thousand years, such was the accepted logic, and all over Europe propositions equally absurd were accepted on equally ridiculous proof.
Since the party that had become dominant in the empire could not furnish works capable of intellectual competition with those of the great pagan authors, and since it was impossible for it to accept a position of inferiority, there arose a political necessity for the discouragement, and even persecution, of profane learning.

The persecution of the Platonists under Valentinian was due to that necessity.