In medieval Icelandic rhet., the verb kenna (við), "make known (by)," was used to explain these expressions: "din" (the "base word" in modern analysis) is "made known" as battle by "of spears" (the "determinant"). The determinant may be in the genitive case, as here, or may attach to the base word to form a compound ("spear-din"); the base word takes the morphological and syntactic form of the concept the k. replaces. In skaldic poetry the determinant could in turn be replaced by another determinant; if "flame of battle" means "sword," then "flame of the din of spears" makes an acceptable k. Snorri Sturluson, the 13th-c. poet and man of letters and the first to attempt a rhetoric of ks., called this example tvíkennt ("twice-2determined") in the commentary to Háttatal in his Edda. If another determinant were added, to make a four-part k., he would call it rekit, "driven." Snorri cautioned against "driven" ks. with more than six parts.

     The relationship between the base word and determinant(s) could be essentially metonymic, as in "Baldr's father" for Odin, or metaphoric, as in the examples above. The ks. of West Germanic poetry, frequently used in connection with variation, tend toward the first category, those of skaldic poetry toward the second. Many skaldic ks. rely on Norse mythology or heroic legend for the links between the parts; thus poetry is the "theft of Odin" because he stole it from the giants. In skaldic poetry the number of concepts for which ks. may substitute is limited to about one hundred, among which warrior, woman, weapons, and battle are well represented. Since the base words tend to be fairly stereotyped (ks. for "woman" often have the name of a goddess as base word, for example), the system is relatively closed, but ks. make up nearly all the nouns in skaldic poetry, and the verbs are not important. Having imposed on themselves this closed system, the skalds exploited it brilliantly. In skaldic poetry the sum of the ks. is, to be sure, greater than their parts, but the best skalds made every word count.

One can scan the glossary of Klaeber's third edition of Beowulf and find the nature of the noun epithet amply illustrated. A good place to begin is under the letter h with the "hilde-" (battle) compounds. We find "hilde-bord" (battle shield), "hilde-cumbor" (battle banner), "hilde-mece" (battle sword), "hilde-ræs" (battle rush), and twenty others. The difference between these straightforward compounds and the kennings is made clear when one compares "hilde-mace" (battle sword) with a kenning for sword, "hilde-leoma" (battle light). All are formulaic in that they are repeated, in Beowulf and elsewhere, and many have their counterparts in similar metrical patterns under different alliterative heads. Battle was one of the richest sources of formulas in Old English poetry; a number of words besides "hilde" convey the idea: "beado," "gud," wæl," and so on. For "hilde-rinc" (warrior) we have "beado-rinc," and so on. They do not necessarily mean the exactly the same thing; usually there are distinctive nuances. They provide the variation that is essential to a poetic based upon repetition. Most of the equivalent epithets, as one would expect, reflect the concerns of a warrior culture: the attributes of the warrior and his weapons and the nature of his lord and his companions.

To understand the role of the kenning, one must realise that the compound metaphor is not merely a word substitution. Instead, the kenning frequently represents more than the actual subject of the metaphor itself by implying the potential of the idea or object it describes. In short, the whole of the kenning is greater than the sum of its parts. The resulting construction therefore provides an intimate, contextual detail and a significantly emotional connotation that a less formal metaphor could not accomplish.

     The skaldic periphrasis for "woman" just cited is a complex puzzle, involving allusion, substitution, and a grammatical trick. The limiting element is not a single word, but is itself a substituting periphrasis: "enforced ransom of the otter" stands for the concept "gold," in allusion to the ransom which three of the Æsir were compelled to pay Hreiðmarr for the killing of his son Ottarr, the gold of the ransom having itself been taken by force from Andvari. Woman is conceived as the giver of gold, selja gulls. Having periphrased the concept "gold" (gull) by ótrs nauðgjöld, the skald then substituted for the word selja, "giver" -- which also means "willow" -- the word eik, which, like selja is a feminine tree-name. But there is a difference between the character of the puzzle involved in periphrasing "gold" as "enforced ransom of the otter" and that presented by "oak" for "giver": the first is a mythological allusion, and in the myth gold was a ransom demanded and paid under duress -- gold is characterized as something which, in a given context, it actually was. But a giver is not an oak: woman, as giver, is called something which woman is not. And here, in the identification of a person or thing with something that it is not, except in a very special and artifical sense, lies the nature of the true kenning; a kenning is not merely a metaphor; it is, in Heusler's words, metapher mit ablenkung. The base-word identifies the referent with something which it is not, except in a specially conceived relation which the poet imagines between it and the sense of the limiting element. An example which is clearer because it involves no play on words is the skaldic hliðar þang, "tang of the hillside," for grass or brush, which is not tang, but is called tang because it grows on the hillside as tang grows in the sea. Similarly "sea of beasts" is a kenning for "earth": earth is the abiding-place of beasts, as the sea is of fish.

     I have used skaldic examples to illustrate the kenning because the extremes to which they carry the principle underlying the figure emphasize the difference between the kenning and other images of similar structure. The Old English kennings are much simpler and more transparent. Hildenædre, "battle-adder," is a kenning for "arrow" or "javelin" (Elene, Judith); garbeam, "spear-tree," is a kenning for "warrior" (Exodus). In these, as in the skaldic kennings, the base-word identifies the referent with something which is it not, except in relation to the concept expressed in the limiting word: an arrow is thought of as stinging those wounded by it in battle, as an adder stings in the field; a warrior stands firm in strife, as a tree stands in the forest; the limiting noun "spear" substitutes for a noun denoting "battle," the sphere in which the warrior functions. In all kennings there is a tension between the concept and the base-word; the limiting word partially resolves the unreality of that relation.

     The qualitative difference between these kennings and such compounds and combinations as "helm-bearer," wave-traverser," "heath-stepper," "breaker of rings" is obvious. These last, unlike kennings, express the concepts for which they stand through and identification of the referent with something which it actually is. In the four metaphorical instances cited by Klaeber, however, we have genuine kennings: "candle of the sky," "gem of heaven" are terms for "sun" in which the base-word calls the referent something which it is not, except in an imagined relation to the sky or the heavens. The sun is neither a candle nor a gem; but it illumines the sky as a candle illumines a room, and it adorns the heavens with its gleam as a gem adorns and shines upon a garment. The body is not a house; but it may be called banhus because it contains the bones as a house contains its occupants. A sword is not a flame; but in the kenning beadoleoma it is imagined as giving forth light in battle as a torch or brand gives light in darkness.

     The kenning is indeed a metaphor; but it is not a direct or a just metaphor. It depends for its effect not upon the listener's recognition that a given thing is so like that with which it is identified that the identification has immediate poetic truth; it depends upon the hearer's ability and willingness to see likeness within unlikeness, and the unlikeness must seem to be dissipated through the limiting word, which expresses an area, or a condition, within which likeness may be imagined. There are metaphors which are not kennings: for example, forstes bend for the ice which "binds" the water in winter; wintergewæde (Phoenix) for the snow which covers the earth. A metaphor is a kenning only if it contains an incongruity between the referent and the meaning of the base-word; in the kenning the limiting word is essential to the figure because without it the incongruity would make any identification impossible.

     Those periphrases which are not kennings, but which possess the same structure as the kenning, and which identify the referent as something which it is, may best be called by the Old Icelandic term kend heiti. A heiti, in its more precise sense, is a substantive simplex; such a heiti becomes kent, that is, "characterized," in terms of some actual quality or relationship, when it is combined with some limiting word. Kend heiti emphasize "a certain quality of a person or thing," as Klaeber says, or one of its aspects or functions. A great many kend heiti denoting persons have as base-word a noun of agency: a king is "breaker of rings"; a warrior is a "helm-bearer." Even kend heiti denoting some animals or objects may have nouns of agency as base-words: a dragon is an "air-flyer," a ship is a "wave-traverser."

     One special variety of kent heiti, very common in both Icelandic and Old English poetry, is called by the Icelanders viðkenning. This is one of two varieties of appellation which Snorri groups together as fornöfn -- that is, as substitutions not for concepts, but for the names of persons. The viðkenning has the structure base-noun combined with limiting genitive; but its base-word is always a term of ownership or of personal relationship (e.g., "owner," "father," "brother," "son," "friend," enemy," "slayer," etc.); and its limiting word is the name of the person or the owned object with whom, or with which, the specified relationship exists, or a recognizable substitute therefor. In skaldic poetry Thor is called "Lord of Bilskirnir"; Njörðr is "father of Freyr"; Freyr is "foe" or "slayer of Beli"; King Olaf I of Norway is "son of Tryggvi." In Old English poetry Beowulf is sunu Ecgðeowes, bearn Ecgðeowes, etc. Hrothgar is Healfdenes hildewisa; Hygelac is bona Ongenþeoes.

     The viðkenning is NOT a variety of kenning, nor does its name imply that it partakes of the nature of the kenning. The word means, simply and literally, "a characterization in terms of" a specific person or named thing; it is derived from the verb kenna, which in rhetoric meant "to make a characterizing periphrasis." Snorri, in his initial classification of the skaldic poetic appellations, carefully excluded the fornöfn from the category of the kenning. The word fornafn is regularly used in the Icelandic grammatical treatises to translate prænomen; and indeed the viðkenning is pronominal in function; it stands for a name. Other types of kend heiti, and all kennings, stand not for names, but for concepts. As fornafn, a viðkenning always stands for the name of one specific individual, and distinguishes him from all others; whereas other kinds of kend heiti, and kennings, describe the referent typically. Thus eodor Scyldinga, "protector of the Shieldings," is a kent heiti applied to Hrothgar, but it could be applied with equal propriety to any Danish king; but the viðkenning sunu Healfdenes, used of Hrothgar after the death of his brothers, could mean no one but Hrothgar. The viðkenning identifies a specific individual, and stands for him alone. It stands lower than any other type of appellation in its poetic quality, which resides entirely in its allusiveness; in its direct and unmistakable identification it is poles apart from the kenning.

     In the use of the viðkenning for the name of any person, there is no intent to mystify, to compel the listener to supply the answer to an unasked question. The scop's audience was thoroughly familiar with royal genealogy and with heroic legend, and recognized instantly the person referred to. The viðkenning at once lost its character as a rhetorical device when it was used with, instead of as a substitution for, the name of the referent. Mago Healfdenes, sunu Frodan, used instead of the name, had the same poetic quality that attaches to any simple literary allusion; but this was instantly lost when the viðkenning stood in close juxtaposition to the name. Thus, in the well-known formula Beowulf maþelode, bearn Ecgðeowes, the combination bearn Ecðeowes is not a viðkenning, but a mere patronymic.

     And therein lies a most important distinction between the viðkenning on the one hand and other varieties of kend heiti and the kenning on the other: whereas the viðkenning loses all poetic quality, and its very existence as an allusion, in combination with the name of the referent, other kind of kend heiti, and kennings, are used freely in Old English poetry either as substitutions for, or side by side with, the literal word for the referent, without losing, in either case, any of their poetic effect. Too much emphasis has been placed upon substitution in Old Norse, but not in Old English. Most frequently, in Old English poetry, we find kennings and kend heiti used as variations of the direct and literal word for the referent, or as variations of one another. Old English poets did not share the fondness of the skalds for mystification; and they carried variation to lengths undreamed of by Norse poets. In Elene 117-120 we find the kenning hildenædran used as a variation for the specific term for the referent, flana scuras, garas; and in Judith 221-222:

In Beowulf 1965b-66a the kenning woruldcandel is explained in the next line by the variation sigel, an ókent heiti (i.e., a poetic simplex) for the referent, the sun. Indeed, it is one of the characteristic traits of Old English poetic style that kenning and heiti are most often used in variations; the variation, rather than kenning or heiti, is, for the poet, the prime consideration; the poetic simplex or periphrasis is the material out of which the variation is made.

     The essence of the kenning is the incongruity between its referent and that which it is called in the base-word, and an artificial resolution of the incongruity through the choice of limiting word. When a ship is called "wain of the roller," it is conceived as moving forward on the rollers which permit it to be thrust down to the water as a wain moves forward on its wheels. The identification is unreal; the very resolution is imperfect, since a wain moves forward not on rollers, but on wheels. Creation and apprehension of such a strained metaphor require an act of intellectual exercise not unlike that required by a riddle. The kent heiti, possessing the same structure as the kenning, embodies not a strained image, not an identification of the referent with something which it is not, but a just metaphor or metonymy; it involves no incongruity, and may be apprehended at once. Its base-word may be anoun denoting the material of which the referent is made, or one of its parts, or one of its functions or qualities; the limiting word expresses the medium or area in which the function is performed, or the object upon which it is performed, or some characterizing attribute (as in fetelhild, wundenstefna) or some quality which gives the thing its value (mægenwudu, ellenweorc).