A collection of source materials on the famous Square of Opposition. Under development. The diagram above is from a ninth century manuscript of Apuleius' commentary on Aristotle's Perihermaneias, probably one of the oldest surviving pictures of the square.

Apuleius' Commentary on the Perihermaneias
Boethius' translation (in Latin) of the Perihermaneias with Edghill's English translation
Edward Buckner's translation of chapters 6 and 7
Natalis on Equipollence
Every man is an animal
Brentano's Logical Innovations
Existential Import

External links
Internet Encyclopedia entry (This is OK)
Wikipedia April 2007 entry (I wrote part of this).
Parsons' SEP entry (I shall be discussing Parson's view at Montreux).
Chapter 2 of Parson's book on medieval logic, which covers similar ground.
Old directions in free logic, by Gyula Klima
Montreux International Congress on the Square. Pictures taken by Edward Ockham

Edward Buckner
London, May 2007

THE LOGIC MUSEUM Copyright (c) E.D.Buckner 2007.