Who is XXX's sister?
Plato
Plato (/ˈpleɪtoʊ/; Greek: Πλάτων Plátōn pronounced (plá.tɔːn) in Classical Attic; 428/427 or 424/423 -- 348/347 BC) was a philosopher in Classical Greece and the founder of the Academy in Athens, the first institution of higher learning in the Western world.