Many otherwise well-educated people have long taken this picture for granted. [Complete lack of science in the Middle Ages] No one has diffused it more widely than astronomer Carl Sagan (1934–1996), whose television series Cosmos drew an audience estimated at half a billion. In his 1980 book by the same name, a timeline of astronomy from Greek antiquity to the present left between the fifth and the late fifteenth centuries a familiar thousand-year blank labelled as a “poignant lost opportunity for mankind.” The timeline reflected not the state of knowledge in 1980 but Sagan’s own “poignant lost opportunity” to consult the library of Cornell University, where he taught. In it, Sagan would have discovered large volumes devoted to the medieval history of his own field, some of them two hundred years old. He would also have learnt that the alleged medieval vacuum spawned the two institutions in which he spent his life: the observatory as a research institution (Islamic civilization) and the university (Latin Europe).

-The Cambridge History of Science: Volume 2 Medieval Science, ed. David C. Lindberg & Michael H. Shank, CUP, New York, ppb. 2015 pp.9-10

H/T Mike Flynn