Thomas Aquinas would strongly disagree with you on the loss of Classical learning (I think you probably mean “training”) in the West.The Middle Ages were considered backward because of the loss of Classical learning in the West (particularly Greek and the great Greek philosophers) and the loss of a united Mediterranean region under Roman rule.
Aquinas was writing shortly after the appearance of some of Aristotle’s works in Latin in the West. But even Aquinas had to read them in translation–no Greek. And most certainly no Hebrew by which to read the Old Testament.Thomas Aquinas would strongly disagree with you on the loss of Classical learning (I think you probably mean “training”) in the West.