How did Islam help preserve and add to classical thought?

Answer 1

During the Dark Ages in Europe Muslim scribes were cataloging works of European Scholars. When the European works were subsequently lost, the Muslims had them in libraries.

Answer 2

Classical European thought??? When you are talking about different cultures in different parts of the world you need to specify which cultural ideas of what classical thought are.

Answer 3

Maybe they saved all the heads they chopped off.