250. Every preposition, but one, in Esperanto has a fixed and definite signification, and great care must be taken to use the preposition which gives the meaning we wish to convey. A careful examination of the list of prepositions in par. [259] will show the errors we should make by translating the English preposition into its apparent corresponding one in Esperanto.
251. The preposition je is the only one in Esperanto without a definite meaning. It should be used only when we have to employ a preposition and are uncertain which we ought to select. We can, however, omit the preposition, and put its complement (noun or pronoun) in the accusative case, provided no ambiguity is likely to arise through the presence of other accusatives in the sentence, as:—Li ĝojas je tio, or, Li ĝojas tion = He rejoices at (or, over) that. There is no Esperanto preposition which gives exactly the English meaning of "at" or "over" in this sense. We might, perhaps, say that these words are part of the verb "to rejoice at," or, "to rejoice over." The nearest Esperanto preposition would be pri or pro = about, or, because of, and we could say Li ĝojas pro tio = He rejoices because of that (see Rule 14, par. [94]).
(a). Je, with the nominative, is generally used before the complement of the adjectives "deep, high, long, thick, wide," but the accusative without a preposition is equally correct.
Examples.—Profunda (alta, longa) je kvin futoj (or, kvin futojn) = Five feet deep (high, long). La rivero estas larĝa je kvindek metroj (or, larĝa kvindek metrojn) = The river is fifty metres wide. We could, however, say, La rivero havas kvindek metrojn da larĝo (or, da larĝeco).
252. Adverb for preposition.—An adverb is often used instead of a preposition and its complement (par. [248] (c)).
Examples.—Li parolas saĝe = He speaks with wisdom, instead of, Li parolas kun saĝeco. Li estis frapata perfortege = He was being struck with great violence, instead of, Li estis frapata kun perfortego.
253. Preposition omitted.—Not only the preposition Je (par. [251]), but also other prepositions, are frequently omitted in Esperanto where we use them in English; but in such case (as stated in par. [68]) their complements must be in the accusative to show the omission. Care, however, must be taken that the omission does not make the phrase ambiguous.
Examples.—Li venos la mardon proksiman (or, en la mardo proksima) = He will come next Tuesday. Mi iros Madridon (or, al Madrido) morgaŭ = I shall go to Madrid to-morrow. Mi lin vidis la dekan (or, en la deka) de Julio = I saw him on the 10th of July. Ni restis en la veturilo du horojn (or, dum du horoj) = We remained two hours in the carriage.
(a). Prepositions are also always omitted between two substantives, when the word nomata = named could be understood (par. [106] (d)), as:—
La urbo (nomata) Parizo = The city of (named) Paris. La monato Septembro = The month of September. Li uzadas la lingvon internacian (nomatan) Esperanto = He uses the international language Esperanto.