II. CASE.
44. In Irish there are five cases—the Nominative, Accusative, Genitive, Dative, and Vocative.
The Nominative case in Irish corresponds to the English nominative when the subject of a verb.
The Accusative corresponds to the English objective case when governed by a transitive verb. The accusative case of every noun in modern Irish has the same form as the nominative, and suffers the same initial changes as regards aspiration and eclipsis.
The Genitive case corresponds to the English possessive case. English nouns in the possessive case or in the objective case, preceded by the preposition "of," are usually translated into Irish by the genitive case.
The Dative case is the case governed by prepositions.
The Vocative corresponds to the English nominative of address. It is always used in addressing a person or persons. It is preceded by the sign a, although "O" may not appear before the English word; but this a is not usually pronounced before a vowel or ḟ.
RULES FOR THE FORMATION OF THE CASES.
N.B.—These rules apply to all the declensions.
45. The Nominative case singular is always the simple form of the noun.