Mia patrino forgesis sian libron = My mother forgot (or, has forgotten) her book. Tiuj infanoj perdis siajn gepatrojn = Those children have lost their parents. La hundo amas sian mastron = The dog loves its master. Oni devas ami sian najbaron, kiel sin mem = One must love one’s neighbour as oneself. N.B.—Sin is here in the accusative owing to ellipsis, the words oni amas after kiel being understood (see par. [105]).
137. In the following three sentences the possessive pronoun does not refer to the subject of the sentence, and therefore we use lia, ŝia, ĝia, or ilia, as the case may be:—
Li vidis mian amikon kaj lian edzinon = He saw my friend and his (his friend’s) wife. Ŝi venis al mi hieraŭ, por ke mi redonu ŝiajn leterojn al ŝi = She came to me yesterday in order that I might return her letters to her. La reĝo amas Johanon kaj lian filon = The king loves John and his son.
N.B.—Here the English does not show whether it is John’s son or his own son whom the king loves, but in Esperanto it is clear it is John’s son, otherwise it would be
sian filon; lian filon is in the accusative here, because the conjunction kaj connects like cases (see par. [266]).
(a). Note in the following examples how the possessive varies in accordance with the construction of the sentence.
El ĉiuj siaj amikinoj, ŝi plej amas Marion = Of all her friends (female), she loves Mary best. (Here siaj refers to ŝi).
El ĉiuj ŝiaj amikinoj, Mario estas le plej amata = Of all her friends, Mary is the most loved. (Here ŝiaj refers to some woman not mentioned.)
Leginte sian libron, li ekdormis = After reading (having read) his book, he fell asleep. (Here sian refers to li, understood in leginte = When he had read his book, he ...). Leginte lian libron, li ekdormis = After reading his book, he fell asleep. (Here lian refers to some man not mentioned, who might have lent him the book.)
Johano, legante sian libron, venkiĝis de dormo = John, while reading his book, was (became) overcome by sleep.