Thereafter, from one’s early twenties and on, one begins the long, slow decline. Some of the mental decline is masked and counteracted by hard work or by increasing wisdom. Thus, at least in some areas of pursuit (but not others), people do not reach their professional or overall mental peaks until later in life. However, there is an underlying decline, at least physically and to some extent also mentally: Hair turns gray or begins to fall out; wrinkles begin to appear and various body parts sag; muscle gives way to fat, as strength does to weakness; and eyesight and hearing begin to fail.37
