CHAPTER IX OF THE MECHANISM OF THE HUMAN MIND Nature of Mechanism. - Its classes, material and intellectual. - Material system, or of vibra- tions. - The intellectual system most probable - from the consideration that thought would otherwise be a superfluity - from the established principles of reasoning from effects to causes. - Objections refuted. - Thoughts which pro- duce animal motion may be - I. involuntary - 2. unattended witk consciousness. - The mind cannot have more than one thought at any one time. - Objection to this assertion from the case of complex ideas- from various mental oper- ations - as comparison - apprehension. - Rapidity of the succession of ideas. - Appli- cation. - Duration measured by consciousness. - 3. a distinct thought to each motion may be unnecessary - apparent from the complexity of sensible impressions. - The mind always thinks. - Conclusion. - The theory applied to the phenomenon...