So far, the first speech element that we have found which we can say
actually "exists" is the word. Before defining the word, however, we
must look a little more closely at the type of word that is illustrated
by _sing_. Are we, after all, justified in identifying it with a radical
element? Does it represent a simple correspondence between concept and
linguistic expression? Is the element _sing-_, that we have abstracted
from _sings_, _singing_, and _singer_ and to which we may justly ascribe
a general unmodified conceptual value, actually the same linguistic fact
as the word _sing_? It would almost seem absurd to doubt it, yet a
little reflection only is needed to convince us that the doubt is
entirely legitimate. The word _sing_ cannot, as a matter of fact, be
freely used to refer to its own conceptual content. The existence of
such evidently related forms as _sang_ and _sung_ at once shows that it
cannot refer to past time, but that, for at least an important part of
its range of usage, it is limited to the present. On the other hand, the
use of _sing_ as an "infinitive" (in such locutions as _to sing_ and _he
will sing_) does indicate that there is a fairly strong tendency for the
word _sing_ to represent the full, untrammeled amplitude of a specific
concept. Yet if _sing_ were, in any adequate sense, the fixed
expression of the unmodified concept, there should be no room for such
vocalic aberrations as we find in _sang_ and _sung_ and _song_, nor
should we find _sing_ specifically used to indicate present time for all
persons but one (third person singular _sings_).

The truth of the matter is that _sing_ is a kind of twilight word,
trembling between the status of a true radical element and that of a
modified word of the type of _singing_. Though it has no outward sign to
indicate that it conveys more than a generalized idea, we do feel that
there hangs about it a variable mist of added value. The formula A does
not seem to represent it so well as A + (0). We might suspect _sing_ of