Euclid, Christoph Clavius - Posteriores libri IX : Accessit liber XVI. De solidorum regularium... - 1589

In 1589 two important works were issued by the century's leading mathematician Christoph Clavius (1538-1612) . Clavius had already issued what became a very popular edition of Euclid in 1574. More a commentary enhancing access to the work than a philological edition of the Greek text, Clavius revised and republished it at least five times, Clavius went beyond the strict bounds of Euclid’s material to introduce new materials, including his own proof of Euclid’s fifth postulate and his solution to the problem of squaring the circle. The broad significance of Clavius’s Euclid for many seventeenth-century mathematicians cannot be overstated.

. In 1589 appeared:

. Posteriores libri IX : Accessit liber XVI. De solidorum regularium cuiuslibet intra quodlibet comparatione. Omnes perspicuis demonstrationibus, accuratisque scholiis illustrati.

. The listed volume is the rarer of the dozens of editions of Euclid's Elements that appeared from 1500 to 1700 and has extensive commentary.

. It is a very thick octavo: 959 [+ 96 index] pages with many in-text illustrations. The cold pressed boards are contemporary (intriguing pen signature on rear board) , while the spine is later (and has pretty cold pressed decorative features) . The whole is in excellent overall condition. Some pages a little browned, other stunningly white, tiny worming (less than one cm) affecting perhaps 40 pages. There are no end papers. There is some old damp staining to some corners.

. The Posteriores libri IX ("Beyond Euclid’s Nine Books") appears to be an extension of Clavius’ Euclid of 1574, in which he considered fifteen books of Euclid. Here we find a sixteenth book added by François de Foix-Candale (1512-1594) . De Foix was a French mathematician and alchemist and a noted geometer who established a Chair of Geometry at the University of Bordeaux in 1591. The three books comprising an addendum to Euclid’s Elements, Books XIV-XVI, all consider the regular polygons and their properties.