46. When the verb in a sentence expresses motion, the word indicating
the place, person or thing toward which the motion is directed is given
the accusative ending. This is also true if the word is the complement
of any preposition which does not itself sufficiently indicate motion
in a certain direction. (The prepositions "al", to, toward, "gxis",
as far as, "tra", through, express motion in the direction of their
complements, and could not well be used except in a sentence whose verb
expresses motion. Consequently the accusative is not used after any of
these three):
Li iris gxardenon, he went to the garden ("gardenward").
La viro iros Bostonon, the man will go to Boston ("Bostonward").
[Footnote: Cf. English "he went home," "he went homeward," etc.]
Li estis en la gxardeno, kaj kuris en la domon,
he was in the garden and ran into the house.
Gxi ne estas sur la tablo, gxi falis sur la plankon,
it is not on the table, it fell upon the floor.
Ili falis sub la tablon gxis la planko,
they fell under the table as far as the floor
(direction expressed by whole prepositional phrase).
Mi iris tra la domo en mian cxambron,
I went through the house into my room.