A favorite liar and servant of mine was a man I once had to drive a brougham.—Thackeray.
In New York I read a newspaper criticism one day, commenting upon a letter of mine.—Id.
What would the last two sentences mean if the word my were written instead of of mine, and preceded the nouns?
About the case of absolute pronouns.
88. In their function, or use in a sentence, the absolute possessive forms of the personal pronouns are very much like adjectives used as nouns.
In such sentences as, "The good alone are great," "None but the brave deserves the fair," the words italicized have an adjective force and also a noun force, as shown in Sec. 20.
So in the sentences illustrating absolute pronouns in Sec. 86: mine stands for my property, his for his property, in the first sentence; mine stands for my praise in the second. But the first two have a nominative use, and mine in the second has an objective use.
They may be spoken of as possessive in form, but nominative or objective in use, according as the modified word is in the nominative or the objective.
III. The Objective.
The old dative case.