But depression is not a sudden disaster. It is more like a cancer: At first its tumorous mass is not even noticeable to the careful eye, and then one day — wham! — there is a huge, deadly seven-pound lump lodged in your brain or your stomach or your shoulder blade, and this thing that your own body has produced is actually trying to kill you. Depression is a lot like that: Slowly, over the years, the data will accumulate in your heart and mind, a computer program for total negativity will build into your system, making life feel more and more unbearable. But you won’t even notice it coming on, thinking that it is somehow normal, something about getting older, about turning eight or turning twelve or turning fifteen, and then one day you realize that your entire life is just awful, not worth living, a horror and a black blot on the white terrain of human existence. One morning you wake up afraid you are going to live.