Aristotle’s Organon comprises six key essays on logic, initially collected by Theophrastus, his successor as head of the Peripatetic school, and given its final form by Andronicus some three centuries later. The six essays are: Categories, On Interpretation, Prior Analytics, Posterior Analytics, Topics and On Sophistical Refutations. One of the principal topics of Aristotle’s focus is syllogism, in which two premises (one major, one minor) lead to a conclusion. This features in Prior Analytics and On Interpretation.

In the other essays, Aristotle considers the structure of being, knowledge and argument. The Organon collection has remained a core text in the study of logic and prompted many commentaries by philosophers down the ages following their translation from Greek into Latin in the 12th century. The translations here are by E. M Edghill, A. J. Jenkinson, G. R. G Mure and W. A. Pickard-Cambridge.