Simplify the following text for a Grade 11 native English-speaking person.
Original: Pierre Gilliard said that Olga had a very `` quick brain '' , with `` good reasoning powers '' and `` a very independent manner , and a gift for swift ( quick ) and entertaining ( funny ) repartee ( replies ) . ''
Simplified: `` The eldest , Olga Nicolaevna , possessed a remarkably quick brain '' , recalled her French tutor , Pierre Gilliard . `` She had good reasoning powers as well as initiative , a very independent manner , and a gift for swift and entertaining repartee . ''