What is the difference between the genitive and the accusative case. I know the endings and the fact that they are used for nouns (with their adjectives) that are the direct object but when do I use what? Thanks.
Ha, some philologist might be useful :). Well, to give you the clue, though, if you want to say you have, see, eat, drink, love, hate, buy (look at the Eclipse by Pink Floyd to find more :) something, use accusative.
OTOH, if you want to say, that you don't have, see, ...- use genitive. If you want to say: 'This is a cat's claw'- (so to express possession- the claw belongs to the cat)- the cat will be in genitive. Hope it helps.
Piotr, is a name and is therefore a personal noun in the nominative case so as an example, ja znam Piotra-I know Piotr. The genitive case may be ownership such as ksiazka Piotra-Piotr's book, or the genitive case may be formed with use of pronouns such as 'z' and 'od', both meaning from and in both these cases the noun takes the genitive case. Ja dostalem ten prezent od Piotra-I got this present from Piotr.
If you want to have, see, know etc. a NON-LIVING, i.e INANIMATE masculine male noun, then the accusative endings are used, e.g. "Widze nowy czarny stól." = I see the new black table vs. "Widze mojego nowego madrego psa." = I see my clever new dog, (ANIMATE LIVING masculine noun) whereby in the latter instance, the genitive case endings are used, since a dog of course is living, a table isn't!
In English too, a "corpse" was once living, yet is still considered an organism, by definition, having at one time been animate, i.e. having an "anima" or "soul". The Germans term the Polish concept of "animate" vs. "inanimate" BESEELT and UNBESEELT nouns, from "Seele", the German word for "soul"!