How was the education learning and knowledge of Europe preserved during the lowest point of the middle ages?

There were several groups of people who preserved culture and learning in the Middle Ages. First of these was the Byzantine Empire, which had schools open during the entire time. The second was the Church, which always had schools and scriptoriums in monasteries. Another was Arabs and other Muslims, who brought their own knowledge, derived from Greece, India, China, and their own scientific inventiveness, to Europe when they invaded Spain in 711. Yet another was Jews who lived throughout Europe and had their own understanding of medicine, philosophy, finance, and law, and who were very good at preserving culture and learning.