Child mortality was highest in tribal societies in the rain forest, and among traditional farmers in the remote rural areas across the world.

Only 9 percent of the world lives in low-income countries. And remember, we just worked out that those countries are not nearly as terrible as people think.

You won’t find any countries where child mortality has increased. Because the world in general is getting better.

The world used to be divided into two but isn’t any longer. Today, most people are in the middle. There is no gap between the West and the rest, between developed and developing, between rich and poor. And we should all stop using the simple pairs of categories that suggest there is.

Describing his moment of euphoria It was almost three o’clock in the morning before the final result of my computations lay before me [...] I could no longer doubt the mathematical consistency and coherence of the kind of quantum mechanics to which my calculations pointed. At first, I was deeply alarmed. I had the feeling that, through the surface of atomic phenomena, I was looking at a strangely beautiful interior, and felt almost giddy at the thought that I now had to probe this wealth of mathematical structures nature had so generously spread out before me. I was far too excited to sleep, and so, as a new day dawned, I made for the southern tip of the island, where I had been longing to climb a rock jutting out into the sea. I now did so without too much trouble, and waited for the sun to rise.

Heisenberg had brilliantly intuited a way of representing the quantum world and asking questions about it using such symbols, while being unaware of matrix algebra. In a few frenetic months, Born, along with Heisenberg and Pascual Jordan, developed what’s now known as the matrix mechanics formulation of quantum physics. In England, Paul Dirac saw the light too when he encountered Heisenberg’s work, and he too, in a series omf papers, independently added tremendous insight and mathematics to the formulation and developed the “Dirac notation” that’s still in use today.

No man ever steps in the same river twice, for it's not the same river and he's not the same man.