Thiu may, quite rightly, note we've had this discussion elsewhere and I regret to say I got severely trounced. But I've found an (older, yes!) quotation that sums up what I've always understood to be a valid point regarding those classical works which survived the sub-Roman and Anglo-Saxon periods and later, and I promised Thiu I would quote it (so he can refute it!):

This is from H. St. L.B. Moss and the Birth of the Middle Ages: 395-814:

"During the ages of transition, the Western Church as a whole definitely feared and distrusted the pagan learning; there are notable exceptions to this attitude, but the uncompromising tradition of Tertullian proved stronger, and finally previaled with the influence of Gregory. In a natural reaction from earlier depreciation of the 'Dark Ages,' stress has recently been laid on the 'humanism' of the medieval Church; but it is not difficult to overstate this view, for it is certain that the sole purpose of education at this time in the West was to train ecclesiastics for the performance of their duties. The knowledge required for an understanding of the Latin services, and - in the case of more advanced pupils - for the study of Christian controversial and expository literature, the computation of Easter, and other festivals, the legal and adminjistrative system of the Church, provided in many cases an admirable curriculum, and the organized life of the monastery, with its regular hours, its library and its economic security, gave opportunities for the preservation of culture in dangerous times which no other institution could have afforded. But the extraordinary, achievements of scholars like Bede and Aldhelm, and, judged by contemporary standards, the high intellectual level of Canterbury, York, Wearmouth and Jarrow in seventh-century England . . . must not blind us to the fact that our gratitude for the preservation of classical literature would have incurred the censure of the most orthodox ecclestiastical authorities, nor cause us to minimize the great gulf which divides the learning of this age from that of Jerome, and still more that of Origen, when all the resources of ancient civilization were still available. For several centuries, these resources had been declining, and the Church further reduced and diluted the supply. Creative thought had long ceased; the taste of the time had turned to epitomes, anthologies, grammars and works of reference. Genuine mastery of the Greek language disappeared wholly from the West; after Boethius there was no real assimilation of Hellnic philosophy. Decorative Greek characters, isolated passages, and words from glossaries are found in Irish manuscripts, and Bede, exceptionally, shows some acquaintance with the Septuagint, but of a creative use of Greek there is no indication. Passive encyclopaedists, like Isidore of Seville and Raban Maur, are the characteristic product of the early Middle Ages - an indication of the stern necessity for the preservation of extant knowledge in face of the barbarism which threatened to engulf it."

The highlighting is something I understand from my reading - that the very idea of reading the pagan authors for knowledge and pleasure would have displeased certain clerics of the time.