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

Our children long for realistic maps of the future that they can be proud of. Where are the cartographers of human purpose?

Nature does not always conform to our predispositions and preferences, to what we deem comfortable and easy to understand.

The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.

In the way that scepticism is sometimes applied to issues of public concern, there is a tendency to belittle, to condescend, to ignore the fact that, deluded or not, supporters of superstition and pseudoscience are human beings with real feelings, who, like the sceptics, are trying to figure out how the world works and what our role in it might be. Their motives are in many cases consonant with science. If their culture has not given them all the tools they need to pursue this great quest, let us temper our criticism with kindness. None of us comes fully equipped.

Even Johannes Kepler, Isaac Newton, Charles Darwin, Gregor Mendel, and Albert Einstein made serious mistakes. But the scientific enterprise arranges things so that teamwork prevails: What one of us, even the most brilliant among us, misses, another of us, even someone much less celebrated and capable, may detect and rectify.

You have to know the past to understand the present.