In many of the books that Liddel owned, there is evidence of personal connections between him and his friends and colleagues.
Perhaps one of the clearest examples of these connections is in a large folio volume containing four separate works, including Ptolemy’s Almagest and Euclid’s Elements.
The Almagest is covered with annotations by Liddel’s teacher Heinrich Brucaeus but it also contains an inscription from Liddel’s “best known, most intimate, and most proven friend,” Cornelius Martini.
Brucaeus taught mathematics and medicine at Rostock until his death in 1593. In addition to Liddel, he taught Cornelis Martinus, Franciscus Parcovius and Tycho Brahe.
The book is annotated in the main by Brucaeus showing the interests, cultural background, work and teaching activity of a Renaissance mathematician. There are minor additions by Liddel and unusually, there is an epigram in Liddel’s hand on the page facing the title page of the Almagest by Angelo Ambrogini (Poliziano): Epitaphum Ptolemy.