EPISTLE.

...the gravity of the cause original: "causae necessitas" and the glory of God, to which this whole work is directed, compel me to speak here a bit more freely about my own arguments than is my usual custom. Yet, however certain and evident I consider them to be, I am not convinced that they are suited to everyone's grasp.

Instead, it is just as in geometry, where many things have been written by Archimedes, Apollonius, Pappus, and others. Although these works are considered by everyone to be evident and certain—because they contain nothing that is not very easy to understand when viewed on its own, and nothing in which the consequences do not accurately cohere with the preceding points—nevertheless, because they are somewhat long and require a very attentive reader, they are understood by only a very few people.

In the same way, although I believe that the arguments I use here equal or even surpass geometric proofs in their certainty and evidence, I think... original: "exiſti-", likely completing "existimo" or "I believe"