> Never heard of the phrase "squeezing blood from stone" because well there is no blood in stones. That's the point. You can't squeeze blood from a stone becau

> Never heard of the phrase "squeezing blood from stone" because well there is no blood in stones. That's the point. You can't squeeze blood from a stone because there isn't any, i.e. it's fruitless to try because you'll always fail. As for "mental toughness" and "chess ability," the idea is that you need both. You could have world-class abilities, but they won't won't help you to win championships if you turn into a quivering pile of nerves at the thought of playing a game in public, for example. Carlsen seems better able to hold his nerve over long periods, allowing him to use his superior chess ability consistently, whereas other players may become exhausted, upset, or distracted more easily.