The nominative case - Its primary function is to indicate which noun or nouns serves or serve as the subject of the sentence. The subject of the sentence is the noun or nouns which perform the action of the verb. A sentence can have more than one subject, for instance, “Caesar and his army attacked Gaul.” In that case, “Caesar” and the “army” are both the subject of the sentence.

The genitive case - The primary function of the genitive case is to show possession, basically, that one noun is owned or in the possession of another noun, for instance, “the man’s house.” The possessive “man’s” would be in the genitive case in Latin. This can also be expressed as “the house of the man.” Note: English has two ways of expressing possession: “of,” or -s’/-’s. ’S is used to express the singular possessive in English, as in “the student’s assignment.” S’ is used to express the plural possessive, as in “the students’ assignments.” Though pronounced the same way, s’ refers to more than one student. 

The dative case - The primary function of the dative case is to indicate which noun is or nouns are the indirect object of the sentence, that is, who or what benefits from the action of the verb. To have the dative case at all in a sentence requires a special type of verb, one whose meaning includes the possibility of benefit, such as, “buy,” “build,” “tell,” “lend,” “sell,” “show,” “give.” As in: “Buy me a diamond,” “Build me a castle,” “Tell me you love me,” “Lend me your fortune,” and “Sell me the space to show you the love I can give you.” English has two ways of indicating an indirect object. It can use the prepositions “to” or “for,” as in, “I gave this to you,” “I did a favor for you.” Or a word can be put in a special place in the sentence, between the verb and the direct object, such as, “I gave you this,” “I did you a favor.”

The accusative case - The primary function of the accusative case is to indicate which noun serves or nouns serve as the direct object of the sentence. The direct object receives the action of the verb. The accusative case is also used to indicate the object of certain prepositions like ad or inter. We’ll learn more about these prepositions later. 

Note: There can be two or more direct objects in a sentence, often when that sentence contains multiple verbs, such as “You will have no problem with English grammar if you study Latin.” There are two direct objects in this sentence. The first is “problem,” the object of “you will have.” The second is “Latin,” the direct object of “study,” the second verb in this sentence, the one inside the if-clause. 

The ablative case - The primary function of the ablative case, at least for now, is to indicate which noun or nouns serve as the object of certain prepositions. By prepositions we mean words like “by, with, from,” but the use of the ablative in Latin is far more pervasive than that. It is in many ways the catch-all case. It can show: means, the instrument with which something was done; manner, the way in which something was done; time, the time at which something was done; separation, that two things are apart from each other; all these and many other uses besides. Wheelock is right to call the ablative case adverbial inasmuch as it usually specifies how something happens, for instance, “with speed” or “in good time” or “by you.” We’ll spend several lessons later in the term learning different uses for the ablative but until then we’ll use the ablative only to serve as the objects of certain prepositions.