Since Maupassant wrote the character of Mathilde I would say that he most certainly agree with the statement. I am inclined, and I would venture to say that most people are too, to agree wholeheartedly. We get one single life to live and it is constantly in motion. One bad choice, one wrong turn, can completely change the course of one's life as he or she knows it, no matter how small and trivial it might seem at the time. For Mathilde, her one wrong choice could have been not swallowing her pride and admitting to Madame Forestier that she had lost the necklace. Her mistake could also have been not being happy with what she had in the first place, her life really wasn't that bad, but it seemed to be to her because she was always looking at others who had so much more. The choices we make throughout life are what make us who we are.