A riddle is a statement or question having a double or veiled meaning, put forth as a puzzle to be solved. Riddles are of two types: enigmas, which are problems generally expressed in metaphorical or allegorical language that require ingenuity and careful thinking for their solution, and conundrums, which are questions relying for their effects on punning in either the question or the answer.
The answer called for by the poem is 'bookworm'. The meaning is metaphoric - the riddle expressing the skepticism of an oral culture in the face of a literacy revolution. The general technique of the riddle form is to refer obliquely to the subject by kenning and other sorts of figurative language; since kennings formed such an important element of alliterative verse forms in the Germanic languages, the riddles served the dual empirical purpose of puzzling the poet's audience and teaching the lore needed to successfully use or understand the poetic language. But riddles also served a more abstract role in Anglo-Saxon education, for they taught their listeners how to track two (or more) meanings at once in a single semantic situation, and a fortiori their very existence demonstrates that the pre-Christian Anglo-Saxons were not inhabiting a thought-world lacking in subtlety and complexity. There are at least eighteen distinct Anglo-Saxon words describing aspects of cognitive skill [frod, ferð, onhæle, degol, cunnan, dyrne, hyge, hygecraft, hylest, heort, þencan, gleaw, sceolon, giedd, mod, sawol, heofodgimme, wis, snot(t)or, wat, swican - the list could be extended], a fact which attests to a culture valuing cognitive skills, albeit in an oral and not literate context. The god Odin was a master of riddle lore, and sparred with several of his foes using contests of riddles. In the Vafthruthnismal, Odin defeats his foe by posing a question only he could possibly know the answer to.
But riddles were not excluive to the Anglo-Saxons and Old Norse; they are an ancient and ubiquitous cultural phenomenon. Oedipus killed the Sphinx by grasping the answer to the riddle it posed (Oedipus Tyrannus, lines 380 onward); Samson outwitted the Philistines by posing a riddle about the lion and the beehive (Judges 14:5-18). In both cases, riddles, far from being mere child’s play, are made to decide matters of life and death. Although Plato reports that ancient Greek children did indeed engage in riddle play (Republic 479c), he also recognized the important function that riddles can play in showing what cannot literally be said about ultimate truths (Letters, book 2, 312d), as does the Hebraic Book of Proverbs which shows "how to understand a proverb and a figure, the words of the wise and their riddles" (Proverbs 1:5-6). Aristotle considered riddles important enough to include discussion of their use in his Rhetoric. He describes the close relationship between riddles and metaphors: “Good riddles do, in general, provide us with satisfactory metaphors; for metaphors imply riddles, and therefore a good riddle can furnish a good metaphor” (1405b4-6). Archer Taylor says in his book English Riddles from Oral Tradition “we can probably say that riddling is a universal art” and cites riddles from hundreds of different cultures including Finnish, Hungarian, American Indian, Chinese, Russian, Dutch and Filipino sources amongst many others. Hamnett analyzes African riddling from an anthropological viewpoint in his article “Ambiguity Classification and Change: the Function of Riddles” [Man 2(1967)pp.379-391]. Scott analyzes Persian and Arabic riddles in “On Defining the Problem of a Structural Unit” [Genre 2(1969)pp.129-142]. Athenaeus of Naucratis (fl. C. 200 AD) complied a copious anthology of ancient Greek riddles citing some 1,250 authors under the title Epitome.
The answer to this charade is "sea-man". Another, composed by Jane Austen herself, is this:
The answer is "hem-lock".
This form of charade appeared in magazines, books, and on the folding fans of the Regency. The answers were sometimes printed on the reverse of the fan, suggesting that they were a flirting device, used by a young woman to tease her beau.
The name "charades" gradually became more popularly used to refer to acted charades. Examples of the acted charades are described in William Thackeray's Vanity Fair and in Charlotte Brontë's Jane Eyre.
The solution here is Teacher.
The highlight here is nadi, or "river".
In J. R. R. Tolkien's The Hobbit, Gollum challenges Bilbo Baggins to a riddle competition; Bilbo wins the competition by asking the riddle, "What have I got in my pocket?" (though he notes that it was not exactly a riddle "according to the ancient rules") which Gollum cannot answer. The answer was the One Ring, which Gollum had lost and Bilbo had found. Although this is more of a simple question than a riddle, by attempting to answer it rather than challenging it Gollum accepted it as a riddle; by accepting it, his loss was binding.
In Norse mythology, the king of the gods, Odin, like Bilbo, won such a contest by the questionable tactic of asking a question to which only he could know the answer. However, as with Gollum, the adversary who accepts such a question is bound to honor the terms of the game.
In the video game, Star Wars: Knights of the Old Republic, the player character can become trapped inside of a Rakatan mind trap in which he or she must engage in a riddle game with the trap's prisoner to escape safely.
In Stephen King's The Dark Tower III: The Waste Lands and The Dark Tower IV: Wizard and Glass, the ka-tet must riddle against Blaine the Mono in order to save their lives. At first Blaine can answer all riddles posed to him by the ka-tet easily, but then Eddie Dean, one of the ka-tet, gains the upper hand when he starts to ask "joke riddles", effectively frustrating Blaine's highly logical mind.
A Riddle Game plays a key role in various versions of Turandot. The suitors need to answer all three questions to gain the Princess's hand, or else they are beheaded - In Puccini's opera Turandot grimly warns Calaf 'The riddles are three, but Death is one'.