Who is Cephalus from Great Dialogues and what is their importance?

Cephalus is the wealthy man who hosts "The Republic" in his home. He and Socrates briefly discuss the benefits and hardships of old age, and Cephalus suggests, to Socrates' delight, that old age is a blessing..... that it frees a man from the uncontrollable passions of his youth. After their discussion, Cephalus leaves the room and does not return.