7.1. Cases and postpositions
Cases are markers of the grammatical roles of nouns. In most European languages, the inflexion of articles, adjectives, and nouns is used to show cases. English pronouns have three cases: the nominative case, the genitive case (possessive case), and the accusative case (objective case). The nominative case is often used for the subject of sentences, and the accusative case is often used as the object of sentences. For instance, the word they are nominative, the word their is genitive, and the word them is accusative. Since common nouns don't have case markings at all to distinguish grammatical roles, English has become full of prepositions. The grammatical role of a phrase is given by its preposition so that you can change the order of phrases without a chance of misunderstanding. For example, you can say both "It rarely snows in Yokohama" and "In Yokohama, it rarely snows," because the preposition in clearly stands for the place. But English has no prepositions to mark the subject and the object, so it uses the word order to determine them. Generally speaking, the fewer case markers (inflexion and adpositions) a language has, the more sensitive the language is to the word order. Chinese is very sensitive to the word order because it doesn't have inflexion at all and it has few prepositions.
In Japanese, cases including nominative and accusative are always shown by postpositions. You can easily see grammatical roles because all phrases are explicitly marked. Japanese has no noun inflexions like English they, their, and them. Memorizing postpositions is much easier than memorising noun inflexions because neither nouns nor postpositions change their spellings.
There is no marker for verbs in Japanese, but you can easily spot them because they are always at the end of sentences. That comes from the head-last rule because a verb is the most important part of a sentence and other phrases including the subject are additional information to the verb.
|Romanization:||Sa ku ra ga sa i ta .|
|Structure:||(noun, cherry blossoms) (nominative marker) (verb, bloomed)|
This sentence means "Cherry blossoms bloomed." Please remember Japanese doesn't care much about the distinctions in English shown by the use (or not use) of the definite article the. The postposition が "ga" is the nominative marker, so the preceding noun さくら "sakura" is the subject of the sentence.
|Romanization:||Ga ka ga e o ka i ta .|
|Structure:||(noun, artist) (nominative marker) (noun, picture) (accusative marker) (verb, drew)|
This sentence means "An artist drew a picture." The postposition を "o" is the accusative marker, so the preceding noun え "e" is the object of the sentence. Note that the hiragana を is ancient and used only for the accusative marker. Other than that, "o" is always written with the hiragana お.
Since cases are given by postpositions, you can change the word order like this:
|Romanization:||E o ga ka ga ka i ta .|
|Structure:||(noun, picture) (accusative marker) (noun, artist) (nominative marker) (verb, drew)|
All you have to do is add appropriate postpositions to nouns and put a verb at the end.