Let us begin with a simple sentence that involves various kinds of concepts--_the farmer kills the duckling_. A rough and ready analysis discloses here the presence of three distinct and fundamental concepts that are brought into connection with each other in a number of ways. These three concepts are "farmer" (the subject of discourse), "kill" (defining the nature of the activity which the sentence informs us about), and "duckling" (another subject[53] of discourse that takes an important though somewhat passive part in this activity). We can visualize the farmer and the duckling and we have also no difficulty in constructing an image of the killing. In other words, the elements _farmer_, _kill_, and _duckling_ define concepts of a concrete order.
[Footnote 53: Not in its technical sense.]
But a more careful linguistic analysis soon brings us to see that the two subjects of discourse, however simply we may visualize them, are not expressed quite as directly, as immediately, as we feel them. A "farmer" is in one sense a perfectly unified concept, in another he is "one who farms." The concept conveyed by the radical element (_farm-_) is not one of personality at all but of an industrial activity (_to farm_), itself based on the concept of a particular type of object (_a farm_). Similarly, the concept of _duckling_ is at one remove from that which is expressed by the radical element of the word, _duck_. This element, which may occur as an independent word, refers to a whole class of animals, big and little, while _duckling_ is limited in its application to the young of that class. The word _farmer_ has an "agentive" suffix _-er_ that performs the function of indicating the one that carries out a given activity, in this case that of farming. It transforms the verb _to farm_ into an agentive noun precisely as it transforms the verbs _to sing_, _to paint_, _to teach_ into the corresponding agentive nouns _singer_, _painter_, _teacher_. The element _-ling_ is not so freely used, but its significance is obvious. It adds to the basic concept the notion of smallness (as also in _gosling_, _fledgeling_) or the somewhat related notion of "contemptible" (as in _weakling_, _princeling_, _hireling_). The agentive _-er_ and the diminutive _-ling_ both convey fairly concrete ideas (roughly those of "doer" and "little"), but the concreteness is not stressed. They do not so much define distinct concepts as mediate between concepts. The _-er_ of _farmer_ does not quite say "one who (farms)" it merely indicates that the sort of person we call a "farmer" is closely enough associated with activity on a farm to be conventionally thought of as always so occupied. He may, as a matter of fact, go to town and engage in any pursuit but farming, yet his linguistic label remains "farmer." Language here 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.