e betrays a certain
helplessness or, if one prefers, a stubborn tendency to look away from
the immediately suggested function, trusting to the imagination and to
usage to fill in the transitions of thought and the details of
application that distinguish one concrete concept (_to farm_) from
another "derived" one (_farmer_). It would be impossible for any
language to express every concrete idea by an independent word or
radical element. The concreteness of experience is infinite, the
resources of the richest language are strictly limited. It must perforce
throw countless concepts under the rubric of certain basic ones, using
other concrete or semi-concrete ideas as functional mediators. The ideas
expressed by these mediating elements--they may be independent words,
affixes, or modifications of the radical element--may be called
"derivational" or "qualifying." Some concrete concepts, such as _kill_,
are expressed radically; others, such as _farmer_ and _duckling_, are
expressed derivatively. Corresponding to these two modes of expression
we have two types of concepts and of linguistic elements, radical
(_farm_, _kill_, _duck_) and derivational (_-er_, _-ling_). When a word
(or unified group of words) contains a derivational element (or word)
the concrete significance of the radical element (_farm-_, _duck-_)
tends to fade from consciousness and to yield to a new concreteness
(_farmer_, _duckling_) that is synthetic in expression rather than in
thought. In our sentence the concepts of _farm_ and _duck_ are not
really involved at all; they are merely latent, for formal reasons, in
the linguistic expression.

Returning to this sentence, we feel that the analysis of _farmer_ and
_duckling_ are practically irrelevant to an understanding of its content
and entirely irrelevant to a feeling for the structure of the sentence
as a whole. From the standpoint of the sentence the derivational
elements _-er_ and _-ling_ are merely details in the local economy of
two of its terms (_farmer_, _duckling_) that it accepts as units of
expression. This indifference of the sentence as such to some part of
the analysis of its words is shown by the fact that if we substitute
such radical words as _man_ and _chick_ for _farmer_ and _duckling_, we
obtain a new material content, it is true, but not in the least a new
structural mold. We can go further and substitute another activity for
that of "killing," say "taking." The new sentence, _the man ta