  We investigated the evolution and transformation of scientific knowledge in
the early modern period, analyzing more than 350 different editions of
textbooks used for teaching astronomy in European universities from the late
fifteenth century to mid-seventeenth century. These historical sources
constitute the Sphaera Corpus. By examining different semantic relations among
individual parts of each edition on record, we built a multiplex network
consisting of six layers, as well as the aggregated network built from the
superposition of all the layers. The network analysis reveals the emergence of
five different communities. The contribution of each layer in shaping the
communities and the properties of each community are studied. The most
influential books in the corpus are found by calculating the average age of all
the out-going and in-coming links for each book. A small group of editions is
identified as a transmitter of knowledge as they bridge past knowledge to the
future through a long temporal interval. Our analysis, moreover, identifies the
most disruptive books. These books introduce new knowledge that is then adopted
by almost all the books published afterwards until the end of the whole period
of study. The historical research on the content of the identified books, as an
empirical test, finally corroborates the results of all our analyses.
