distinct definitions.

CHAPTER VI.

TERMINOLOGY AND NOMENCLATURE.

Not only must words have a fixed and knowable meaning; but also, no
important meaning should be without its word: that is, there should be a
name for everything which we have often to make assertions about. There
should be, therefore, first, names suited to describe all the individual
facts; secondly, a name for every important common property detected by
comparing those facts; and, thirdly, a name for every _kind_.

First, it conduces to brevity and clearness to have separate names for
the oft-recurring combinations of feelings; but, as these can be defined
without reference back to the feelings themselves, it is _enough_ for a
_descriptive_ terminology, if there be a name for every variety of
elementary feeling, since none of these can be defined, or indicated to
a person, except either by his having the sensation itself, or being
referred through a known mark to his remembrance of it. The meaning of
the name when given to a feeling is fixed, in the first instance, by
convention, and must be associated _immediately_, not through the usage
of ordinary language, with the feeling, so that it may at once recall
the latter. But even among the elementary feelings, those purely mental,
and also sensations, such as those from disease, the identity of which
in different persons cannot be determined, cannot be exactly
_described_. It is only the impressions on the outward senses, or those
inward feelings connected uniformly with outward objects (and,
consequently, sciences, such as botany, conversant with outward
objects), which are susceptible of an exact descriptive language.

Secondly, there must also be a separate name for every important common
property recognised through that comparison of observed instances which
is preparatory to induction (including names for the classes which we
artificially construct in virtue of those properties). For, although a
definition would often convey the meaning, both time and space are
saved, perspicuity promoted, and the attention excited and concentrated,
by giving a brief and compact name to each of the new _general
conceptions_, as Dr. Whewell calls them, that is, the new results of
abstraction. Thenceforward the name nails down and clenches the
unfamiliar combination of ideas, and suggests its own definition.

Thirdly, as, besides the artificial classes which are marked out from
neighbouring classes by d