Power entails responsibility. Having used our power to transform nature and society, we have put the survival of both at risk. So our responsibility, from now on, is to ensure that both may endure. To do this, we must add to our present obligations a sense of obligation toward future generations – not only toward our fellow humans, but toward the world as a whole and all the living beings that comprise it. We must care as deeply for their distant future as we do for our own immediate future. These are not conditional obligations based on our uncertainty about the state of the planet; they are absolute obligations. As such, we may not choose between them or subordinate one to the other. We may not sacrifice tomorrow for today. Indeed, the only thing worthy of our attention today is that which will ensure a long-term tomorrow – for our life and the life of the world.