Petrus RamusPetrus Ramus (1515-1572) was an outspoken, revolutionary teacher and thinker. He viewed mathematics as a subject essential to all learning, and revolutionised the teaching of mathematics at the University of Paris where he lectured. He promoted mathematics and astronomy as subjects of serious study and greatly enhanced the status of mathematics but his abilities as a mathematician, along with the rigid views that he held, meant that his work was not always viewed with sympathy.

Liddel made many marginal notes in his copy this work. Ramus was critical of Copernicus’ theory of planetary motion because it was hypothetical, not based on actual observation. Liddel, in turn, was very critical of Ramus, noting that his postulation is ‘impossible and absurd’ and that ‘he laughs at hypotheses.’ In doing this, Liddel echoed the opinions of Tycho Brahe who met Ramus in 1569 and found his views on hypotheses difficult to accept.