Original: Inspired by Jean-Jacques Rousseau's idea that geniuses are self-taught, Wollstonecraft chose a rational, self-taught heroine, Mary, as the central character of her novel.
Simplified: Wollstonecraft was inspired by Jean-Jacques Rousseau's idea that "geniuses are self-taught", so Wollstonecraft made Mary, the main character, a self-taught heroine.