The technique european painters developed of modeling mass in two dimensions through value, which is demonstrated in da vinci’s the virgin and saint anne with the christ child and john the baptist, is called

Acurious child asked his mother: “mommy, why are some of your hairs turning grey? ” the mother tried to use this occasion to teach her child: “it is because of you, dear. every bad action of yours will turn one of my hairs grey! ” the child replied innocently: “now i know why grandmother has only grey hairs on her head.”