ular,
curved, square, elliptical; and the terms of Arithmetic to express the
degrees of weight, elasticity, temperature, pitch of sound. When other
means fail, qualities are suggested by the names of things which exhibit
them in a salient way; figures by such terms as amphitheatre, bowl-like,
pear-shaped, egg-shaped; colours by lias-blue, sky-blue, gentian-blue,
peacock-blue; and similarly with sounds, smells and tastes. It is also
important to express by short terms complex qualities, as harmony,
fragrance, organisation, sex, symmetry, stratification.

(iii) In the explanation of Nature we further require suitable names for
processes and activities: as deduction, conversion, verification,
addition, integration, causation, tendency, momentum, gravitation,
aberration, refraction, conduction, affinity, combination, germination,
respiration, attention, association, development.

There may sometimes be a difficulty in distinguishing the terms which
stand for qualities from those that express activities, since all
qualities imply activities: weight, for example, implies gravitation;
and the quality heat is also a kind of motion. The distinction aimed at
lies between a quality as perceived by means of an effect upon our
senses (as weight is resistance to our effort in lifting; heat, a
sensation when we approach fire), and that property of a body which is
conceived to account for its energy (as gravitation that brings a body
to the ground, or physical heat that expands an iron bar or works an
engine). The former class of words, expressing qualities, are chiefly
used in description: the latter class, expressing activities, are
chiefly needed in explanation. They correspond respectively, like
classification and explanation, with the static and dynamic aspects of
Nature.

The terms of ordinary language fall into the same classes as those of
science: they stand for things, classes of things, parts, or qualities,
or activities of things; but they are far less precise in their
signification. As long as popular thought is vague its language must be
vague; nor is it desirable too strictly to correct the language whilst
the thought is incorrigible. Much of the effect of poetry and eloquence
depends upon the elasticity and indirect suggestiveness of common terms.
Even in reasoning upon some subjects, it is a mistake to aim at an
unattainable precision. It is better to be vaguely right than exactly
wrong. In the criticism of manners,