CV.
The Assumption of a Final Cause in the structure of each part of animals and plants is as inevitable as the assumption of an Efficient Cause for every event. The maxim that in organized bodies nothing is in vain, is as necessarily true as the maxim that nothing happens by chance. (ix. 6.)
CVI.
The Idea of living beings as subject to disease includes a recognition of a Final Cause in organization; for disease is a state in which the vital forces do not attain their proper ends. (ix. 7.)
CVII.
The Palætiological Sciences depend upon the Idea of Cause: but the leading conception which they involve is that of historical cause, not mechanical cause. (x. 1.) 25
CVIII.
Each Palætiological Science, when complete, must possess three members: the Phenomenology, the Ætiology, and the Theory. (x. 2.)
CIX.
There are, in the Palætiological Sciences, two antagonist doctrines: Catastrophes and Uniformity. The doctrine of a uniform course of nature is tenable only when we extend the nation of Uniformity so far that it shall include Catastrophes. (x. 3.)