Complex sentence: In Trevor-Roper's view, another theme of early modern Europe was expansion overseas in the form of colonies and intellectual expansion in the form of the Reformation and the Enlightenment.
Split into simpler sentences: In Trevor-Roper's view, one of the major themes of early modern Europe was expansion. By expansion, he meant both overseas expansion in the form of colonies, and intellectual expansion in the form of the Reformation and the Enlightenment.