Like every other destruction of optimism, whether in a whole civilisation or in a single individual, these must have been unspeakable catastrophes for those who had dared to expect progress. But we should feel more than sympathy for those people. We should take it personally. For if any of those earlier experiments in optimism had succeeded, our species would be exploring the stars by now, and you and I would be immortal.

No precautions, and no precautionary principle, can avoid problems that we do not yet foresee. We need a stance of problem-fixing, not just problem-avoidance.

The quantum theory of parallel universes is not the problem, it is the solution. It is not some troublesome, optional interpretation emerging from arcane theoretical considerations. It is the explanation - the only one that is tenable - of a remarkable and counter-intuitive reality.

Where we have good, testable explanations, they then have to be tested, and we drop the ones that fail the tests.

The brain is the only kind of object capable of understanding that the cosmos is even there, or why there are infinitely many prime numbers, or that apples fall because of the curvature of space-time, or that obeying its own inborn instincts can be morally wrong, or that it itself exists.

Feeling insignificant because the universe is large has exactly the same logic as feeling inadequate for not being a cow.

If you can’t program it, you haven’t understood it.