THE CASES 1279
Of the cases belonging to the Indo-European language, Greek has lost the free use of three: instrumental, locative, and ablative. A few of the forms of these cases have been preserved ( cross341, cross1449, cross1535); the syntactical functions of the instrumental and locative were taken over by the dative; those of the ablative by the genitive. The genitive and dative cases are therefore composite or mixed cases.
N.—The reasons that led to the formation of composite cases are either (1) formal or (2) functional. Thus (1) χώρᾳ is both dat. and loc.; λόγοις represents the instr. λόγοις and the loc. λόγοισι; in consonantal stems both ablative and genitive ended in -ος; (2)
Through the influence of one construction upon another it often becomes impossible to mark off the later from the original use of the genitive and dative. It must be remembered that since language is a natural growth and Greek was spoken and written before formal categories were set up by Grammar, all the uses of the cases cannot be apportioned with definiteness.1281
The cases fall into two main divisions. Cases of the Subject: nominative (and vocative). Cases of the Predicate: accusative, dative. The genitive may define either the subject (with nouns) or the predicate (with verbs). On the nominative, see cross938 ff.1282
The content of a thought may be expressed in different ways in different languages. Thus, πείθω σε, but persuadeo tibi (in classical Latin): and even in the same language, the same verb may have varying constructions to express different shades of meaning.
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].