only, viz., antaŭ = before, and post = after, require care in making their meaning clear.
In the following remarks on prepositions the examples given of their use are placed under the various classes that their English rendering would assign to them; but we must bear in mind that, in accordance with Rule 14, every Esperanto preposition, except je, has a defined and constant meaning (par. [250]). This defined meaning is given at the head of each preposition. The meanings given in the classes are only the various English renderings that can be given to the preposition (see English prepositions, pars. [260], [261]).
REMARKS ON THE PREPOSITIONS.
259 (1). Al = To, towards.
Denotes approximation or addition.
Approximation = To, towards.
Examples.—Li venis al ni = He came to (or towards) us. Mi iras al Parizo, or, Mi iras Parizon = I am going to Paris. If al be omitted, Parizon must be in the accusative of direction. Ni ne vidas, ĉar la lumo estas kaŝata al ni per la kurtenoj = We do not see, because the light is hidden from (towards) us by the curtains.
N.B.—Kaŝata al, not de, which, after a passive participle, means "by"; but independently of this, al is logically used after kaŝi, in the sense of "to hide from"; as:—Sed pro kio kaŝi al li vian amon? = But why conceal from him your love?
Addition = To.
Examples.—Mi donis akvon al la birdoj = I gave water to the birds. La rozo apartenas al Teodoro = The rose belongs to Theodore. Donu vestaĵon al la malriĉuloj = Give clothing to the poor.