There's a very rare book on ebay now: OPERA PHILOSOPHICA by Rene Descartes -1692

Published by Friderici Knochii: Francofurti (Frankfurt) - 1692. This First Edition book, bound in its original full calf with original spine label. Some light worming damage to head of spine not affecting text. Foxing in places; text not fragile; overall condition is very good. All sections total 522 pp. Thick Octavo. Six parts in one volume. Many dozens of figures and illustrations. The important and historical book also bears the armorial bookplate of Prince Franz Josef II of Liechtenstein, (1906-1989), ("Ex Libris Liechtensteinianis")
OPERA PHILOSOPHICA by Rene Descartes -1692 - Ultra-rare - eBay (item 170366746512 end time Aug-10-09 14:43:10 PDT)