Last Friday, I passively observed a conversation about Russian grammar between two native Russian speakers. They were counting the cases of the Russian noun. Enjoying native fluency, they do not really need to know the cases. They are unconsciously competent in the language. Other than writers, language enthusiasts, teachers and very astute students, most native speakers cannot explain, in detail, the grammatical features of their language. This is true of most native English speakers too. For example, most English speakers (educated and otherwise) cannot name the many English tenses. Those who assume that English has three tenses are case in point.
Back to the story, the two Russians recited an acronymic sentence that they learned in school and agreed on six cases. I could be silent no more. How could they forget the beloved vocative case? No one really agrees with me here, but I stand my ground. Wikipedia explains the vocative case here (though even in that article they deny the existence of a vocative Russian case). The vocative identifies the addressee. For example, in the sentence, “You’re being stubborn, Mike, about this grammar thing.” – ‘Mike’ has a vocative meaning (though in modern Russian it would still be nominative).
I concede that the vocative is not what is used to be. In fact, as Wikipedia correctly points out, in Russian you will find this case still in use only in some old proverbs and poetry, and when personally addressing God. I only make issue of this case because of the last point.
'God' in Russian is ‘Бог’. To call out to God, the Russian vernacular calls for the vocative phrase ‘Боже мой’, which means ‘My God!’ In modern speech it is often used irreverently (as it often is in English). However, the phrase occurs in the Russian Bible 250 times; as in Psalms 8:1 (and verse 9):
Господи, Боже наш! Как величественно имя Твое по всей земле!
Which I translate like this:
Lord, our God! How awesome (majestic, wonderful) is Your name in all the earth!
For me, that settles the case for the Russian vocative. Okay, maybe not in general use, but important remnants of past grammatical richness remain.
I pray everyday that more Russians would begin to use the vocative case as exampled above. That is, that more would reverently and with repentant hearts call unto the God of all creation! And that is why I contend that Russian has seven cases, and not six. The seventh case merely needs revival.