Who does Cosimo meet in a neighbor's garden as he explores through the trees?

Playing among them, he also discovers a golden-haired little girl about his age, singing and swinging from a swing tied to a tree in her garden. When she drops her apple, Cosimo draws his rapier to pierce it and return it, from his lofty perch, to the intriguing girl to whom it belongs. In talking with the little girl, he learns she is acquainted with a group of fruit thieves--Cosimo has always considered his distance from such boys a point of pride.