s of Nature. But if a
definite theory of their origin both generally and severally, whether
out of ether-vortices, or groups of electric corpuscles, or whatnot,
shall ever gain acceptance, similarity of genesis or causation will
naturally be the leading consideration in classifying the chemical
elements. To find common principles of causation, therefore, constitutes
the verification of every Natural Classification. The ultimate
explanation of nature is always causation; the Law of Causation is the
backbone of the system of Experience.

CHAPTER XXII

NOMENCLATURE, DEFINITION, PREDICABLES

Sec. 1. Precision of thought needs precision of language for the recording
of such thought and for communicating it to others. We can often
remember with great vividness persons, things, landscapes, changes and
actions of persons or things, without the aid of language (though words
are often mixed with such trains of imagery), and by this means may form
judgments and inferences in particular cases; but for general notions,
judgments and inferences, not merely about this or that man, or thing,
but about all men or all kinds of things, we need something besides the
few images we can form of them from observation. Even if we possess
generic images, say, of 'horse' or 'cat' (that is, images formed, like
composite photographs, by a coalescence of the images of all the horses
or cats we have seen, so that their common properties stand out and
their differences frustrate and cancel one another), these are useless
for precise thought; for the generic image will not correspond with the
general appearance of horse or cat, unless we have had proportional
experience of all varieties and have been impartially interested in all;
and, besides, what we want for general thought is not a generic image of
the appearance of things, though it were much more definite and fairly
representative than such images ever are, but a general representation
of their important characters; which may be connected with internal
organs, such as none but an anatomist ever sees. We require a symbol
connected with the general character of a thing, or quality, or process,
as scientifically determined, whose representative truth may be trusted
in ordinary cases, or may be verified whenever doubt arises. Such
symbols are for most purposes provided by language; Mathematics and
Chemistry have their own symbols.

Sec. 2. First there should be "a name for every important