Early medieval manuscripts of only four authors (Pliny, Macrobius, Martianus Capella, Calcidius) carried late Roman astronomical knowledge to the centers of learning in Carolingian Europe. Originally the sources had no illustrations. Careful copyists annotated the texts if clarification was needed—by glosses and comments and with illustrations. In this way first heliocentric motions of the inner planets Mercury and Venus were introduced centuries before Copernicus. A comprehensive digital archive published in Edition Topoi allows to study all available documents of four centuries of manuscript transmission. It will be the basis of an analysis of guiding methodology of knowledge transmission in early medieval Europe.