So, my optimism is rooted in the fact that for almost over 200 years every year has gotten a little bit better when we look at the scientific evidence. And while it's possible that... next year everything could change, that everything could collapse and fall to the ground, statistically, probabilistically it won't it will continue because 200 years has gone and next year it probably will continue. But if you look at the kind of current political regime around the world and the factors of pressures, environmental pressures, the pressures of distraction that we have from the new media, then I think you have to resort to hope. In the long term, optimists decide the future. It's the optimists who create all the things that are going to be most important in our lives, because it was optimists who built and invented all the things that are now important in our current lives. And I think people behave better when they're optimistic. There's absolutely a need to be critical and doubtful and skeptical and... even pessimistic. Just like if you have a car you have to have brakes. You can't have a car, no matter where it is, without brakes. But it's the engine, the optimistic engine that keeps going and going and refuses to stop and is only concerned about going forward that really drives a car.