“Bad days come in degrees. They are not all equally bad. And the really bad ones, though horrible to live through, are useful for later. You store them up. A bank of bad days. The day you had to run out of the supermarket. The day you were so depressed your tongue wouldn’t move. The day you made your parents cry. The day you nearly threw yourself off a cliff. So if you are having another bad day you can say, Well, this feels bad, but there have been worse. And even when you can think of no worse day – when the one you are living is the very worst there has ever been – you at least know the bank exists and that you have made a deposit.”