1. Generalisation 594 2. Distinction of Generalisation and Analogy 596 3. Two Meanings of Generalisation 597 4. Value of Generalisation 599 5. Comparative Generality of Properties 600 6. Uniform Properties of all Matter 603 7. Variable Properties of Matter 606 8. Extreme Instances of Properties 607 9. The Detection of Continuity 610 10. The Law of Continuity 615 11. Failure of the Law of Continuity 619 12. Negative Arguments on the Principle of Continuity 621 13. Tendency to Hasty Generalisation 623 CHAPTER XXVIII. ANALOGY. 1. Analogy 627 2. Analogy as a Guide in Discovery 629 3. Analogy in the Mathematical Sciences 631 4. Analogy in the Theory of Undulations 635 5. Analogy in Astronomy 638 6. Failures of Analogy 641 CHAPTER XXIX. EXCEPTIONAL PHENOMENA. 1. Exceptional Phenomena 644 2. Imaginary or False Exceptions 647 3. Apparent but Congruent Exceptions 649 4. Singular Exceptions 652 5. Divergent Exceptions 655 6. Accidental Exceptions 658 7. Novel and Unexplained Exceptions 661 8. Limiting Exceptions 663 9. Real Exceptions to Supposed Laws 666 10. Unclassed Exceptions 668 CHAPTER XXX. CLASSIFICATION. 1. Classification 673 2. Classification involving Induction 675 3. Multiplicity of Modes of Classification 677 4. Natural and Artificial Systems of Classification 679 5. Correlation of Properties 681 6. Classification in Crystallography 685 7. Classification an Inverse and Tentative Operation 689 8. Symbolic Statement of the Theory of Classification 692 9. Bifurcate Classification 694 10. The Five Predicates 698 11. Summum Genus and Infima Species 701 12. The Tree of Porphyry 702