We humans look rather different from a tree. Without a doubt we perceive the world differently than a tree does. But down deep, at the molecular heart of life, the trees and we are essentially identical.

One of the reasons for its success is that science has a built-in, error-correcting machinery at its very heart. Some may consider this an overbroad characterization, but to me every time we exercise self-criticism, every time we test our ideas against the outside world, we are doing science. When we are self-indulgent and uncritical, when we confuse hopes and facts, we slide into pseudoscience and superstition.

When Kepler found his long-cherished belief did not agree with the most precise observation, he accepted the uncomfortable fact. He preferred the hard truth to his dearest illusions, that is the heart of science.

But down deep, at the molecular heart of life we're essentially identical to trees.

At a few hundred kilometers altitude, the Earth fills half your sky, and the band of blue that stretches from Mindanao to Bombay, which your eye encompasses in a single glance, can break your heart with its beauty. Home you think. Home. This is my world. This is where I come from. Everyone I know, everyone I ever heard of, grew up down there, under that relentless and exquisite blue.

[Kepler] preferred the hard truth to his dearest illusions, and that is the heart of science.