In his famous Crisis of the Early Italian Renaissance Hans Baron treated the Dominican political thinker Ptolemy of Lucca as purely medieval, his ideas totally separate from the doctrine that Baron named civic humanism. However, in an unpublished, and previously-unstudied, manuscript written more than a decade earlier, Baron maintained that Ptolemy's ideology evolved into something quite close to civic humanism. He attempted to prove this through a comparison of early and late work of Ptolemy and through an analysis of Ptolemy's (...) process of composition of his De Regimine Principum. This article analyses Baron's arguments and in general supports them, with some qualifications. Baron's manuscript supports the conclusions previously published by Blythe and is also significant in what it reveals about the intellectual evolution of one of the twentieth century's most significant historians of political thought. (shrink)