OBS. 17.—Surely, without some imperative reason, we ought not, in English, to resort to such an assumption as is contained in the following Rule: “Sometimes the relative agrees in person with that pronoun substantive, from which the possessive pronoun adjective is derived; as, Pity my condition, who am so destitute. I rejoice at thy lot, who art so fortunate. We lament his fate, who is so unwary. Beware of her cunning, who is so deceitful. Commiserate our condition, who are so poor. Tremble at your negligence, who are so careless. It shall be their property, who are so diligent. We are rejoicing at thy lot, who hast been so fortunate.”—Nixon’s Parser, p. 142. In his explanation of the last of these sentences, the author says, “Who is a relative pronoun; in the masculine gender, singular number, second person, and agrees with thee, implied in the adjective thy. RULE.—Sometimes the relative agrees in person, &c. And it is the nominative to the verb hast been. RULE.—When no nominative comes between the relative and the verb, the relative is the nominative to the verb.”—Ib., p. 143. A pupil of G. Brown’s would have said, “Who is a relative pronoun, representing ‘thy,’ or the person addressed, in the second person, singular number, and masculine gender; according to the rule which says, ’A pronoun must agree with its antecedent, or the noun or pronoun which it represents, in person, number, and gender:’ and is in the nominative case, being the subject of hast been; according to the rule which says, ’A noun or a pronoun which is the subject of a finite verb, must be in the nominative case.’ Because the meaning is—who hast been; that is, thy lot, or the lot of thee, who hast been.”
OBS. 18.—Because the possessive case of a noun or pronoun is usually equivalent in meaning to the preposition of and the objective case, some grammarians, mistaking this equivalence of meaning for sameness of case, have asserted that all our possessives have a double form. Thus Nixon: “When the particle of comes between two substantives signifying different things, it is not to be considered a preposition, but the sign of the substantive’s being in the possessive case, equally as if the apostrophic s had been affixed to it; as, ‘The