For years I've been stressing with regard to UFOs that extraordinary claims require extraordinary evidence.

We've tended in our cosmologies to make things familiar. Despite all our best efforts, we've not been very inventive. In the West, Heaven is placid and fluffy, and Hell is like the inside of a volcano. In many stories, both realms are governed by dominance hierarchies headed by gods or devils. Monotheists talked about the king of kings. In every culture we imagined something like our own political system running the Universe. Few found the similarity suspicious.

Coal, oil and gas are called fossil fuels, because they are mostly made of the fossil remains of beings from long ago. The chemical energy within them is a kind of stored sunlight originally accumulated by ancient plants. Our civilization runs by burning the remains of humble creatures who inhabited the Earth hundreds of millions of years before the first humans came on the scene. Like some ghastly cannibal cult, we subsist on the dead bodies of our ancestors and distant relatives. - Dr. Carl Sagan

If we're capable of conjuring up terrifying monsters in childhood, why shouldn't some of us, at least on occasion, be able to fantasize something similar, something truly horrifying, a shared delusion, as adults?

But amid much elegance and precision, the details of life and the Universe also exhibit haphazard, jury-rigged arrangements and much poor planning. What shall we make of this: an edifice abandoned early in construction by the architect?

Where we have strong emotions, we're liable to fool ourselves.

Human beings grew up in forests; we have a natural affinity for them. How lovely a tree is, straining toward the sky.