In the first four books of the Odyssey, Athena appears in three different disguises. What are they and why does she use them?

Book 2 - Mentor, Athena takes the form of Telemachus to gain a ship and gear for his voyage to Sparta. Then Mentor again.

Book 3 - Mentor at the court of Nestor. She transforms into a vulture and flies off from their meeting w/Nestor and his sons.

Book 19 - Athene is invisible but holding a bright burning lamp so that Odysseus and Telemachus can hide the weapons in the great hall. Telemachus remarks on the strange illumination.

Book 20 - again Athena speaks (in the form of a lady) chides Odysseus to not getting some rest and sleep before the upcoming battle.

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