CHAP. XXXIV.: On Sagacity - Aristotle, Posterior Analytics 
Aristotle’s Posterior Analytics, trans. E.S. Bouchier, B.A. (Oxford: Blackwell, 1901).
About Liberty Fund:
Liberty Fund, Inc. is a private, educational foundation established to encourage the study of the ideal of a society of free and responsible individuals.
The text is in the public domain.
Fair use statement:
This material is put online to further the educational goals of Liberty Fund, Inc. Unless otherwise stated in the Copyright Information section above, this material may be used freely for educational and academic purposes. It may not be used in any way for profit.
- Introductory Note.
- Book I.
- Chap. I.: Whether a Demonstrative Science Exists
- Chap. II.: What Knowing Is, What Demonstration Is, and of What It Consists
- Chap. III.: A Refutation of the Error Into Which Some Have Fallen Concerning Science and Demonstration
- Chap. IV.: The Meaning of ‘distributive,’ ‘essential,’ ‘universal’
- Chap. V.: From What Causes Mistakes Arise With Regard to the Discovery of the Universal. How They May Be Avoided
- Chap. VI.: Demonstration Is Founded On Necessary and Essential Principles
- Chap. VII.: The Premises and the Conclusion of a Demonstration Must Belong to the Same Genus
- Chap. VIII.: Demonstration Is Concerned Only With What Is Eternal
- Chap. IX.: Demonstration Is Founded Not On General, But On Special and Indemonstrable Principles; Nor Is It Easy to Know Whether One Really Possesses Knowledge Drawn From These Principles
- Chap. X.: The Definition and Division of Principles
- Chap. XI.: On Certain Principles Which Are Common to All Sciences
- Chap. XII.: On Questions, And, In Passing, On the Way In Which Sciences Are Extended
- Chap. XIII.: The Difference Between the Demonstration and Science of a Thing’s Nature and Those of Its Cause
- Chap. XIV.: The Figure Proper to Demonstrate Syllogism
- Chap. XV.: On Immediate Negative Propositions
- Chap. XVI.: On Ignorance Resulting From a Defective Arrangement of Terms In Mediate Propositions
- Chap. XVII.: On Ignorance Resulting From a Defective Arrangement of Terms In Immediate Propositions
- Chap. XVIII.: On Ignorance As Resulting From Defective Sense Perception
- Chap. XIX.: Whether the Principles of Demonstration Are Finite Or Infinite
- Chap. XX.: Middle Terms Are Not Infinite
- Chap. XXI.: In Negations Some Final and Ultimate Point Is Reached Where the Series Must Cease
- Chap. XXII.: In Affirmations Some Final and Ultimate Point Is Reached Where the Series Must Cease
- Chap. XXIII.: Certain Corollaries
- Chap. XXIV.: Whether Universal Or Particular Demonstration Is Superior
- Chap. XXV.: That Affirmative Is Superior to Negative Demonstration
- Chap. XXVI.: Direct Demonstration Is Superior to Reduction Per Impossible
- Chap. XXVII.: What Science Is More Certain and Prior, and What Less Certain and Inferior
- Chap. XXVIII.: What Constitutes One Or Many Sciences
- Chap. XXIX.: Concerning Many Demonstrations of the Same Thing
- Chap. XXX.: On Fortuitous Occurrences
- Chap. XXXI.: Sense Perception Cannot Give Demonstrative Science
- Chap. XXXII.: On the Difference of Principles Corresponding to the Difference of Syllogisms
- Chap. XXXIII.: The Distinction Between Science and Opinion
- Chap. XXXIV.: On Sagacity
- Book II.
- Chap. I.: On the Number and Arrangements of Questions
- Chap. II.: Every Question Is Concerned With the Discovery of a Middle Term
- Chap. III.: The Distinction Between Definition and Demonstration
- Chap. IV.: The Essence of a Thing Cannot Be Attained By Syllogism
- Chap. V.: Knowledge of the Essence Cannot Be Attained By Division
- Chap. VI.: The Essence Cannot Be Proved By the Definition of the Thing Itself Or By That of Its Opposite
- Chap. VII.: Whether the Essence Can In Any Way Be Proved
- Chap. VIII.: How the Essence Can Be Proved
- Chap. IX.: What Essences Can and What Cannot Be Proved
- Chap. X.: The Nature and Forms of Definition
- Chap. XI.: The Kinds of Causes Used In Demonstration
- Chap. XII.: On the Causes of Events Which Exist, Are In Process, Have Happened, Or Will Happen
- Chap. XIII.: On the Search For a Definition
- Chap. XIV.: On the Discovery of Questions For Demonstration
- Chap. XV.: How Far the Same Middle Term Is Employed For Demonstrating Different Questions
- Chap. XVI.: On Inferring the Cause From the Effect
- Chap. XVII.: Whether There Can Be Several Causes of the Same Thing
- Chap. XVIII.: Which Is the Prior Cause, That Which Is Nearer the Particular, Or the More Universal?
- Chap. XIX.: On the Attainment of Primary Principles
- Appendix. Prior Analytics. Book II.
- Chap. XXIII.: On Induction
- XXIV.: On Example
Sagacity is a rapid perception of the middle term, or cause, resulting from a consideration of the major and minor terms.
Sagacity is a faculty for hitting upon the middle term in an imperceptible moment of time. For instance, suppose some one, seeing that the moon always has its bright side turned towards the sun, quickly inferred that this was so because the moon receives its light from the sun; or again, seeing someone conversing with a rich man, inferred that he was doing so in order to borrow money; or again inferred that the reason why two persons were friends of one another was that both were enemies of a third person. On seeing the major and minor of the syllogism the sagacious man is able to perceive all the causes or middle terms. Thus: Let A represent ‘having its bright side towards the sun’; B ‘lighted from the sun;’ C ‘the moon.’ Now B, ‘lighted from the sun,’ is true of C, the moon; A, ‘having their bright side towards the body from which the light is received’ is true of all objects denoted by B. Hence A is true of C because it is true of B.