Among the numerous cases found in primitive Aryan (Indo-European) and so well preserved in Sanskrit and ancient Greek, the one that has best resisted the corrosive tendencies found in all languages is undoubtedly the genitive. The preservation in E Sc may be partly due to the sound by which it was most often expressed (s), but probably even more to the fact, that the meaning of this case was better defined than that of such cases as the dative or accusative, and that there seems to be a natural desire to have a convenient way of expressing relation between two notions of the kind indicated by the genitive (`belonging to' in the widest sense, as in Shelley's clothes, wife, father, poems, death etc.). Therefore we find also, even in languages which have a prepositional group corresponding to the English genitive, a set of pronouns to express the same relation, the so-called possessive pronouns (my clothes, etc.).
Nearly all constructed languages use a preposition instead of a genitive ending, generally de or di, taken from the Romanic languages, whence the greater part of their vocabulary is also taken. But corresponding to the personal pronouns they all have possessive pronouns, generally modelled on the Romanic forms, and often embodying some of the irregularities of these, or creating new irregularities of their own. Occ has the following forms, those in parenthesis being the corresponding personal pronouns: mu (mi), tu (tu), su (il, illa, it, se), nor (noi), vor (vo), lor (illi) - thus without any real system. Z simply added his adjective ending -a to the personal pronouns: mia, via, lia, etc., which is systematic enough; and Ido took over the same system, adding -a to its personal pronouns, which are somewhat different from the Esperanto ones. But Z also imaginned a kind of genitive in -s, to be used only in his table of "correlatives", namely ies anyone's, kies whose, ties of such, chies everyone's, and nenies no one's. These were not imitated by Ido.
In Novial we naturally have prepositional combinations, e.g. li tragedies de Shakespeare. But it has been possible by the side of this to devise a perfectly regular means of forming genitives of substantives and pronouns, not only the personal ones, and the basis of all these formations is not invented a priori, but taken from national languages. This is done by the addition of -n: from me `I' we have men, which reminds one of E mine, D mein, same way sen, cp. D sein, Sc sin, F son. This is analogically extended to all other forms, e.g. li sinioron, where we may also compare the German inflexion des herrn, des bären, etc. In Finnish all genitives end in n. This form is particularly useful in cases like these: men patron kontore, kel vu vidad yer my father's office which you saw yesterday. Li doktoron filio, kel es tre richi. Li filio del doktoro, kel es tre richi.
The formation of these genitives is easy enough with words in the singular, as -n here always comes after a vowel; in the plural we must add -en after the plural mark s: li homosen laboro the men's work. This leads to regular forms like nusen, etc. I subjoin a list of some pronomial forms: men vun lon lan len sen nulon nulan nulen quon quan quen my your his her his or her no one's whose (interr.) nusen vusen losen lasen lesen li altresen omnesen our your (you people's) their the others' all's. Other forms are easy enough to form from all kinds of pronouns; thus from the relative kel: li profesoro kelen libres nule lekte whose books no one reads.
A friend writes: "Nusen, vusen, lesen are impossible: why not take nor, vor, lor as Occ?" My reply is that I myself at first felt nusen, etc., as rather unpleasant, but have come to like them better: they have at any rate the advantage of being regularly built up without any new element and of admitting the differentiation lesen, losen, lasen; besides, nusen, vusen resemble S nuestro, vuestro and P nosso, vosso more than the Occ forms nor, vor do. Lor is from I loro, F leur, but nor, vor are arbitrary modifications of the Romanic forms. This is one of the points where individual tastes come into consideration.
As in other constructed languages a combination with the preposition a takes the place of a dative case: lo donad a me e a men fratres chokolate e kukes he gave (to) me and my brothers and sisters chocolate and cakes.
Is a separate accusative form necessary? Occ has acc. forms in the personal pronouns: me (I place the nom. in prenthesis: mi), te (tu), le (il), la (illa), les (illi), further quem (qui, who), thus without any attempt at systematization; the other pronouns have no acc., and the same is true of adjectives and substantives. Z forms an acc. everywhere, in adjectives and substantives as well as in pronouns (but not in the article), by the addition of -n: la bonan homon, la bonajn homajn, min, lin, etc. The use of the acc. is required whenever a word is the object of a verb (but not after prepositions). This, at any rate, is much more consistent than the rule of Occ, but it cannot be denied that Zamenhof by his strict rule has created a great difficulty for his followers, who at any moment have to have the grammatical analysis of each sentence at the tip of their tongues. Esp in this respect is more particular than even such highly inflected languages as Latin, German or Russian, for in these cases there are a great many forms which do not distinguish the accusative from the nominative, thus always in the neuter, often in the plural, etc. (L templum, montes, D das gesicht, die berge, eine frau), and I do not see that any great inconveniences arise from this, any more than from the fact that in E F I P S Sc and other languages neither substantives nor articles nor adjectives have separate acc. forms. Esp in this respect is like the man who always carries an umbrella (and even insists on putting it up), no matter how fine the weather is.
And yet Z necessarily has cases in which the object as such is not marked, thus in the numerals and in the curious use of the adverbial form which he recommends with the special purpose of getting rid of the constraint of the acc.: mi konas multe da homoj instead of multajn homojn, I know many people. In 1894 Zamenhof for a short time advocated the total abolishment of the accusative.
Ido keeps the acc. ending -n, but does not make its use compulsory and specially recommends it in the case of inversion: ilun me konocas, ne ilua spozino, him I know, but not his wife; mea amiko quan vu vidis my friend whom you have seen - thus very often with interrogative and relative pronouns. But it may be doubtful whether a separate case sign is really required even in such sentences, if we insist on the word-order that comes most natural to all West-Europeans as well as to the Chinese, namely with the subject before the verb, and as close to it as circumstances allow. There is no ambiguity possible in the English sentences I quote in Language, p.344, thus, among others: "Talent, Mr. Micawber has; capital, Mr. Micawber has not." "Even Royalty has not quite their glow and glitter; Royalty you might see any day, driving, bowing, smiling. The Queen had a smile for every one; but the Duchess no one, not even Lizzie, ever saw."
Therefore I have no hesitation in recommending the use of the unchanged form even in inverted sentences like these: lo me konosa, ma non lon marita; men amiko kel vu ha vida; similarly in questions: Qui fema lo admira? What woman does he admire? Qui fema admira lo? What woman admires him?
Still, many people would prefer a mark of the accusative to be used in those rare cases in which ambiguity might be feared, and the best ending seems to be -m, which is an ordinary Latin ending and is found in E him, them , Dan ham, dem (where it is true that it was originally a dative, but is now an "accusative" as well): lon me konosa plu bonim kam vum, different from kam vu. But it should be noted that this school example shares the defect of many constructed examples: it is not quite natural, for if the contrast is between two subjects it is not natural to put him first (I know him better than you, i.e. than you do), and if the object is placed first, the contrast will be between two objects: "Him I know better than you" will be understood as meaning "better than I do you, i.e. than you do), and no ambiguity is caused by you being in the common case. Cp. also the use with a proper name: "Smith you know better than Mill." In all such cases those who are afraid of ambiguity will do well to repeat the verb or use other turns.
NOTE. - In one of his numerous schemes of slightly modified Esp Mr. R. de Saussure (Antido) has imagined the use of a proposed e instead of an ending for the acc. The idea is not at all bad, but e was not very well chosen, and em would be better as having some connexion with national languages. Such a preposition would be convenient with proper names, where the addition of an ending is not always possible; it might even be used when the object is a whole clause (which Antido does not mention): Em quand lo sal veni me non sava Just when he is to come I don't know. But though this device appeals to me in some moods, I dare not recommend it to my fellow interlinguists.
Idists have imagined one case in which the use of the acc. would be convenient in what is generally looked upon as a predicative: Quo divenas aquo per varmigo? Glacio. Quon divenas aquo per varmigo? Vaporo. (What becomes water through heating? Ice. What does water become through heating? Steam.) It would perhaps be simpler and clearer in such cases to use the preposition en [E into (JC)] (cp. D zu etwas werden): Aque deveni en vapore per varmiso, etc. Similarly on fa butre fro milke. In both cases the transition from one state to another is indicated by means of prepositions that primarily express movement in space.