Quote Originally Posted by rouloubole View Post
Hello everyone. In order to practice, I am currently starting to read a book ( Обломов ). I read very slowly and try to understand everything, especially the use of cases, since, some of you may know, it is somthing hard for me at the moment

so I encountered this sentence :


which, i know, roughly translates to " thought, like a bird, walk freely on his face " ( something like this, sorry, I have the french translation of the book, so I am translating this too, I hope you understand )

What I don't understand is the use of the cases.

вольной и птицей are in instrumental form ; and

лицу is in accusative form ( If i'm not mistaking )

anyone could explain me why they are used like this ? thank you in advance
You're right that вольная птица ("a free bird", or perhaps "a free-spirited bird" would be better) is in the instrumental here. The instrumental has multiple functions -- among other things, it can translate English "like" or "as". (I assume the French would be something like comme un oiseau libre, but I don't actually speak French.)

The Russian instrumental can also show "agency" after passive verbs ("Oblomov was written by Goncharov."), or "instrument" ("He wrote it with a pen.") or "accompaniment" ("I went to the beach with my family."), and there are other important uses besides -- it's one of the most grammatically versatile noun-cases.

As for лицу, the nominative is лицо (neuter). You're correct that -у/-ю marks the accusative singular of feminine nouns with a nominative singular that ends in -а/-я, but it marks the dative singular of neuter and masculine nouns. And it's dative simply because the preposition по requires the dative when the meaning is "across, along, over." So, по лицу means "across/over his face."
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