LXXX.
We have an Idea of Symmetry; and an axiom involved in this Idea is, that in a symmetrical natural body, if there be a tendency to modify any member in any manner, there is a tendency to modify all the corresponding members in the same manner. (vii. 1.)
LXXXI.
All hypotheses respecting the manner in which the elements of inorganic bodies are arranged in space, must be constructed with regard to the general facts of crystallization. (vii. 3.) 20
LXXXII.
When we consider any object as One, we give unity to it by an act of thought. The condition which determines what this unity shall include, and what it shall exclude, is this;—that assertions concerning the one thing shall be possible. (viii. 1.)
LXXXIII.
We collect individuals into Kinds by applying to them the Idea of Likeness. Kinds of things are not determined by definitions, but by this condition:—that general assertions concerning such kinds of things shall be possible. (viii. 1.)
LXXXIV.
The Names of kinds of things are governed by their use; and that may be a right name in one use which is not so in another. A whale is not a fish in natural history, but it is a fish in commerce and law. (viii. 1.)