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I couldn’t miss Percy’s fifteenth birthday,” Poseidon said. “Why, if this were Sparta, Percy would be a man today!” "That’s true,” Paul said. “I used to teach ancient history.” Poseidon’s eyes twinkled. “That’s me. Ancient history.

"Percy Jackson and the Battle of the Labyrinth". Book by Rick Riordan, books.google.ru. March 5, 2009.
I couldn’t miss Percy’s fifteenth birthday,” Poseidon said. “Why, if this were Sparta, Percy would be a man today!” That’s true,” Paul said. “I used to teach ancient history.” Poseidon’s eyes twinkled. “That’s me.