_Art._ 1. The Idea of Affinity 2. Is not to be made out by Arbitrary Rules. 3. Functions of Living things are many, 4. But all lead to the same arrangement. 5. This is Cuvier's principle: 6. And Decandolle's. 7. Is this applicable to Inorganic Bodies? 8. Yes; by the agreement of Physical and Chemical Arrangement. BOOK IX. THE PHILOSOPHY OF BIOLOGY. CHAP. 1. ANALOGY OF BIOLOGY WITH OTHER SCIENCES. 169 _Art._ 1. Biology involves the Idea of Life. 2. This Idea to be historically traced. 3. The Idea at first expressed by means of other Ideas. 4. Mystical, Mechanical, Chemical, and Vital Fluid Hypotheses. CHAP. II. SUCCESSIVE BIOLOGICAL HYPOTHESES 174 _Sect._ I. _The Mystical School._ _Sect._ II. _The Iatrochemical School._ _Sect._ III. _The Iatromathematical School._ _Sect._ IV. _The Vital Fluid School._ _Sect._ V. _The Psychical School._ {xi} CHAP. III. ATTEMPTS TO ANALYSE THE IDEA OF LIFE 195 _Art._ 1. Definitions of Life, 2. By Stahl, Humboldt, Kant. 3. Definition of Organization by Kant. 4. Life is a System of Functions. 5. Bichat. _Sum_ of Functions. 6. Use of Definition. 7. Cuvier's view. 8. Classifications of Functions. 9. Vital, Natural, and Animal Functions. 10. Bichat. Organic and Animal Life. 11. Use of this Classification. CHAP. IV. ATTEMPTS TO FORM IDEAS OF SEPARATE VITAL FORCES, AND FIRST, OF ASSIMILATION AND SECRETION 203 _Sect._ I. _Course of Biological Research._ _Art._ 1. Observation and New Conceptions. _Sect._ II. _Attempts to form a distinct Conception of Assimilation and Secretion._ _Art._ 2. The Ancients. 3. Buffon. Interior Mould. 4. Defect of this view. 5. Cuvier. Life a Vortex. 6. Defect of this view. 7. Schelling. Matter and Form. 8. Life a constant Form of circulating Matter, &c.