The Complete Works of Archimedes

...others had perceived that there is a proportionality in these figures. Therefore, I should not hesitate to compare them with the results reached by other geometers, and with those things which were thought to be greatly superior among the investigations of illustrious men concerning solids: namely, that every pyramid is a third part of the prism having the same base as the pyramid and an equal height, and that every cone is a third part of the cylinder having the same base as the cone and an equal height. For although these properties were by nature inherent in these figures, even though many worthy geometers existed before the illustrious one, it happened that they were unknown to all, and were perceived by no one. It will now be possible for those who are able to examine these matters; indeed, we ought to have published these things while Conon was still living, for we consider him to have been most able to understand these things and to give a fitting judgment upon them. But since we judge it well to communicate them to those who are devoted to mathematics, we send to you the proofs having written them out, by which it will be possible for those conversant with such studies to examine them thoroughly.

Circular library stamp at the bottom of the page from the Royal Palatine Library of Parma (Regia Bibliotheca Palatina Parmensis).