The use of na is justified in many ways. Na is a Russian preposition that can be used among others as an accusative reinforcer and a few other usages like signifying the attainment of an object after at a short movement’s range. It is bound to be accepted like another Russian preposition was, krom, which does a beautiful job French ne que also does but in a more cumbersome way. It must not be forgotten that Esperanto has Slavic origins in great part, as it resembles a Slavic language having shed most of its native vocabulary for international words. The equivalent of na can be found in many other major languages : Classical Arabic (together with classical Hebrew and other Semitic languages), though it does have an accusative, uses a prepositional equivalent in many contexts where the latter sound stylistically more appropriate, when for instance it comes to an action noun derived from a verb : you can treat like like a verb by giving a direct object complement in the accusative form (which goes for the most time unpronounced) or like a noun, in which latter case subjects in the nominative form turn into complements introduced by min and accusative form complements turn into indirect complements introduced by ilaa (« towards » among others) which means exactly what na means in Esperanto and in the Russian language, both an accusative reinforcer and attainment of object close at hand : it is clearly a preposition of direction, but towards a graspable object rather than towards a mere place. Together with a verb of movement like iri or veturi it means finding the object at the end of the move : nairi, like its Russian counterpart naidti, means more or less trovi but after having walked, whereas naflugi could be employed for a bird or a reconnoitering plane. In Esperanto you can theoretically put an accusative after an action noun to mean the direct object of the action expressed by a noun in ado, but many writers find an expression such as post la konstruado mian domon rather weird and counter-intuitive. I for one rather write la konstruado (fare) de tiu arĥitekto mian domon, or la konstruado de mian domon, but far more E-o users would object to the presence of an accusative after de than to the presence of na. I would like to be authorized to write la konstruado (fare) de la arĥitekto na mia domo, or la konstruado (fare) na mia domo, or la fina venko de Esperanto na la imperia angla en la UNO. National languages such as English are forced in such a case to devise a different prepositional accusative replacement for each action noun, such as England’s victory over Napoleon or Poe’s depiction of the house of Usher, which gives much complexity to the language, a complexity one should try not to import in Esperanto. Anything that can avoid Esperanto to fall into like idiomatism, as is advised by Wahringen in his Plena Analiza Gramatiko, is welcome. Of course na could also replace, when resulting in greater clarity (when for instance the direct object comes last after a long sentence) accusative of direct object of a verb quite in the same way al quite often replaces accusative of directional motion verb, but judging from what happened in other languages most of its practical will tend to gravitate around the use for direct objects of action nouns.

Esperanta "na" and Russian "на" are different things. The first means accusative, the second means "on"

Such a long text to say nothing interesting or useful.

Ĝis, Novatago (blogo / 7 + 1)

Au contraire, I find this part

Miville:
In Esperanto you can theoretically put an accusative after an action noun to mean the direct object of the action expressed by a noun in ado, but many writers find an expression such as post la konstruado mian domon rather weird and counter-intuitive.

very interesting especially since the preposition "de" has too many meanings (10 according to PIV). One of them is to denote object "Post la konstruado de mia domo...", which I find hard to grasp after first been taught to decipher "de" to indicate possession then agent in passive voice then... For me "Post la konstruado mian domon..." is more natural, but I haven't even heard about such possibility before Miville's writing.

How heretic it may sound, but I also think, that the Ido-solution to split the E-o "de" into three "di" (possession), "da" (agent) and "de" (starting point) has its merits.

Я love to krokodili

MiMalamasLaAnglan:
I have a question about de. When I say that something is done by someone, should I say io estis farata de iu, or should I say io estis farata per iu?

Also, because da is already a word, the Ido system would not work well. I personally think that a genitive case could solve this problem, but that's not going to happen.

Has there ever been a generally-accepted major change in Esperanto grammar?

No, per is reserved to be used with diverse tools. You can't use it with humans, unless you literally e.g. hammer with a human. Some use far (de) to denote agent, to differentiate it clearly.

I think, that Ido uses other expression for da in "kiom da" type expressions, thus freeing da for agent.

There have been a couple of big disputes, like the Ata-ita-diskuto for which Akademio de Esperanto has given their judgement.

But there are also slow changes as should be in any living language. A gender neutral third person pronoun is a recent one. An eye-opener for me to the verb system was an article here in Lernu by the same Miville, where they explained, how there were originally five tenses, but now only three.

MiMalamasLaAnglan,

If you are interested in development of the verb tenses, I strongly recommend to read the article by Miville. The bottom line is, that originally E-o made a clear distinction between tense and aspect – like Polish and Russian (perhaps all Slavic languages) do. This distinction was lost, when E-o gained ground among Germanic and Romance language speakers.

Io estis farita de iu is the correct form with regard to the ata-ita-diskuto.

The -iĝi verb forms denote, that the subject becomes something instead of doing it to an object. English is notoriously poor to make this distinction.

He opens the door : Li malfermas la pordon (He makes the door to open)
The door opens : La pordo malfermiĝas (The door becomes open for some unspecific reason)

Since fariĝis is in the active voice, de in that context can't denote agent. Theoretically it could mark object, but in any case io fariĝis de iu doesn't make sense.

As a general rule it is almost always better to use oni, when you want express passive voice. Oni is called indefinite pronoun and corresponds to the man passive in most Germanic languages (English being an exception again). In other words oni faris ion translates to man hat etwas getan in German or man har gjort någonting in Swedish. In English this would be something like "(some unspecified) someone did something" or "something was done".

The topic, when to use de and when el, would be pretty long – and a hard one, not least because of the multiple meanings of de (and IMHO some of the meanings are contradictory). Try to wade through the entries in PIV .

Mi uzas "je" kiam mi ne volas uzi "n". Ekzemple:

"Mi petas je rajto" por "Mi petas rajton"
"Mi batas en je pordo" por "Mi batas en pordon"

Tamen, mi ne scias se "je" estas akceptebla en tiujn okazojn:

Se mi korekte komprenis la mencitan afiŝon de Miville, E-o origine havis sekvajn verboformojn

perfekta aspekto

• prezenco (as-formo): –
  
• preterito (is-formo): faris/ekbezonis
  
• futuro (os-formo): faros/ekbezonos

neperfekta aspekto

• prezenco (as-formo): faras/bezonas
  
• preterito (is-formo): faradis/bezonis
  
• futuro (os-formo): farados/bezonos

depende de, ĉu la verbo fundamente havas perfektan (fari) aŭ neperfektan (bezoni) karakteron. Sed la parolantoj de ne-slavaj lingvoj ne komprenis tiajn karakterojn, kaj oni pli malpli forlasis ek- kaj -ad formojn.

Pri la uzo de "de" kaj "el" vidu mian afiŝon (en la angla) ĉi tie en Lernu.

(In principle one should stick to the language the thread is marked to be in. However slipping to E-o from another language is more tolerated than vice versa.)

MiMalamasLaAnglan:
Thanks for that. However, I have a question about de and el. Why don't fali de tablo and eliri el urbo use the same preposition? Is that because eliri starts with "el-"? I will try to learn the differences between de and el.

Nedankinde. A rule of thumb is, that the E-o prepositions should be understood rather literally. Fali de tablo but eliri el urbo has to do with the openness of the starting point. A table is an open space, while a town is a closed one. Or in other words something, say a ball, isn't (normally) inside a table, but on it before falling off. You are most likely in a town, not on it before leaving it.

This literal reading means, that you have to be careful, when translating non-E-o idioms to E-o. For instance in English you can ride on a train, but "rajdi sur trajno" means, that you bestride on a train's roof. Even taking a train can cause funny mental images, so the safest way is to "veturi per trajno".

Prepositions can be hard. For me "aĉeti en vendejo" causes a mental image, where one keeps buying in the store without finding a way out. To buy and leave the store with the goods you bought is "aĉeti el vendejo" to me. Or my favourite mental image misunderstanding. "Fingroj sur mano" raises a macabre image at me, that some chopped one's fingers off and strewed them on the hand. While for me natural "fingroj en mano" raises at some an equally macabre image, where chopped fingers are stuffed into one's hand.