αὐτός

• Declined like 2-1-2 pattern adjectives with exception in the neuter nominative and accusative singular:
• does not have the ν (nu) case ending, hence it is αὐτό
• this is the same sub-pattern of 2-1-2 seen in the definite article ὁ,ἡ,τό

αὐτός is used in 3 distinct ways:

1) 3rd person pronoun (he, she, it)
2) Intensive Adjective (himself, herself, itself) - usually in predicate position
3) Identical Adjective, e.g. “the same man” - usually in attributive position

1) 3rd Personal Pronoun [he, she, it] (12.8)

• Unlike 1st and 2nd personal pronouns (I, you), αὐτός has gender for obvious reasons: ‘he’, ‘she’, ‘it’ are masculine, feminine and neuter, respectively.
• Case is determined by function in sentence, e.g.
  • Genitive: τοὺς ἀδελφοὺς αὐτοῦ “his brothers”
  • Dative: προσήνεγκαν αὐτῷ δῶρα “they offered to him gifts”
• Gender and Number are determined by its antecedent (the word to which it refers)
• Gender includes grammatical as well as natural gender
• In the oblique cases (non-nominative), it is most often used this way

2) Adjectival Intensive (12.9-10)

• as an adjective in the predicate position (usually), translate with the reflexive pronoun: “he himself”
• is usually emphatic
• ὁ ἄνθρωπος αὐτὸς or αὐτὸς ὁ ἄνθρωπος = “the man himself”
• since it is not required (verb contains subject implicitly), it is sometimes emphatic
• not to be confused with the predicate adjective, i.e. not “the man is himself”
• can also be used with 1st and 2nd personal pronouns: ἐγὼ αὐτός “I myself” or σὺ αὐτός “you yourself”
• Also known as the Intensive Pronoun
• As with any other adjective it must agree with what it modifies in case, gender, and number
• Used this way, it is most often in the nominative case, modifying the subject, e.g. Ἰησοῦς αὐτὸς “Jesus Himself”

3) Identical Adjective (12.11)

• as an adjective usually in the attributive position “same”. This is the least common of the 3 usages of αὐτός
• e.g. ὁ αὐτὸς ἄνθρωπος “the same man” or ὁ ἄνθρωπος ὁ αὐτὸς = “the man, the same one” i.e. “the same man”
• As with any other adjective it must agree with what it modifies in case, gender, and number, e.g. ὁ αὐτὸς ἄνθρωπος, not ὁ αὐτοῖς ἄνθρωπος
• Least frequent of the 3 usages

See Smyth on αὐτός