+DEFINITIONS.
Person is that modification of a noun or pronoun which denotes the speaker, the one spoken to, or the one spoken of.
The First Person denotes the one speaking.
The Second Person denotes the one spoken to.
The Third Person denotes the one spoken of.
Case is that modification of a noun or pronoun which denotes its office in the sentence.
The Nominative Case of a noun or pronoun denotes its office as subject or as attribute complement.
The Possessive Case of a noun or pronoun denotes its office as possessive modifier.
The Objective Case of a noun or pronoun denotes its office as object complement, or as principal word in a prepositional phrase+.