Zamenhof gave Esperanto one strikingly unnatural feature – the ‐A ‐E ‐I ‐O ‐U endings (see Section G), superficially resembling the sets of “thematic vowels” in Latin‐ or Russian‐style declensional systems. Forcing words into this pattern may add that little bit of extra distortion to the roots, but it was intended to serve three purposes:
Class‐Marking – if all nouns end in ‐O
this makes it easier for learners to find their way around a
Now, this part did work to some extent. Unfortunately… listeners don't benefit from a rule that ‐I marks an infinitive and ‐O marks a noun if they can't tell the marker vowel from any other I or O‑sound. After all, sentences are heard as streams of noises, rather than as sequences of discrete words. Sure, readers can see the spaces between words… but if it was just for readers, what was wrong with the old German trick of capitalising nouns? Besides, all the “little words” learners need most help with are left outside the system: ili is the pronoun “they” and maltro is the adverb “too little”.
Class‐Switching – any given root can take any
one of the endings, reducing the number of separate dictionary
entries required: a verb can become an adjective, or a noun can
become an adverb, without retaining any trace of its history.
Unfortunately… this radically artificial approach has unpleasant effects. For a start, a single noun may be associated with more than one adjective – take for instance the roots viv‐, sun‐, dent‐. As nouns they mean “life, sun, tooth”, but the adjectives are ambiguous in each case between “pertaining to” and “richly supplied with” the noun (“biotic/lively”, “solar/sunny”, “dental/toothy”). Even when the class‐switching could work neatly, it often doesn't: see Appendix W on the haphazard behaviour of roots like timo “fear” and nauzo “disgust”.
Class‐Abstraction – the roots themselves are
classless, so there's no need to memorise whether viv‐ is
basically a verb, noun, or whatever.
Unfortunately… as soon as anyone else looked at this scheme, it became apparent that it simply didn't work. The only way Zamenhof's morphological shambles could be sorted out was by abandoning the doctrine of class‐abstraction and declaring a basic category for each root in the dictionary. Thus for instance bros‐ (“brush”) is inherently a noun, while komb‐ (“comb”) is inherently a verb – kombo means “an act of combing”, and the meaning “tool for combing” requires the compound komb‐ilo (no, ilo and ili aren't related).
Most unfortunately of all, this attempt to break and reset Esperanto's backbone was implemented as a “quick fix”, with as few detectable alterations to the published grammar as possible, rather than as an honest attempt to eradicate the problem. Many of my Esperantist correspondents have themselves been unaware of these retrospectively imposed cryptoclasses – they aren't mentioned at all in “Teach Yourself Esperanto”, despite their effects on the meanings of affixes. For example, ‐ad on a verb‐root implies a long‐running process, such as tern‐ado, “constant sneezing”, while on a noun‐root it forms an ersatz verbal noun, such as kron‐ado, “a (single) crowning”.
And thus Esperanto has wedged itself between the two stools of naturalism and regularity. People familiar with Romance languages often expect the ‐A ending in mi estis la triA (“I was the third”) to signal feminine agreement, which of course it doesn't. But the word tria isn't underlyingly an adjective‐root, and isn't here modifying a noun, so why does it get an ‐A?