LECTURA SUPER SECUNDA PARS DIGESTI VETERIS is the oldest treasure held by Livraria Lello and a veritable testimony to the history of the press. This is a rare incunabulum - a book printed with moveable type, an innovative practice invented and popularised by Gutenberg that was at the origin of the printing press - and afterwards, withstood the passing of the centuries. This work was written by Bartolo de Sassoferrato, a very important 14th century jurist and commentator on Roman law, whose stated principles held great influence in Italy, Spain, Portugal, and Germany. He was Professor of Law in Perugia and leader of a group of Italian jurists who in the mid-14th century wrote a Roman Civil Code. His group applied the Justinian Code and the Roman Civil Code as the foundations from which they derived various concepts and general principles deployed in the Europe of their time. The importance of this work in the national context is evident with examples found in the royal collections of kings João I and Duarte. More important was the in 1426 commission issued by King João for some of Bartolo's works to be translated into Portuguese. This LECTURA SUPER SECUNDA PARS DIGESTI VETERIS is one of the first texts detailing the subjectivity of laws and forms the fifth part of Bartolo de Sassoferrato's comments on the Roman Civil Code. This authentic museum piece furthermore reveals the medieval tradition of hand decoration as its first folio is beautifully illuminated with two columns of printing wrapped in a beautiful floral motif coupled with a beautiful gilt and coloured capital with the remainder of the text decorated with simple but beautiful capitals in red and blue.