Carl Sagan spoke fluently between biology and geology and astrophysics and physics. If you move fluently across those boundaries, you realize that science is everywhere; science is not something you can step around or sweep under the rug.

'Carl Sagan: A Life,' though a riveting tale, tells as much about the all-too-human feelings of jealousy and resentment as it does about the individual who inspired them.

The disturbing truth about science communication is that we have theories and ways of delivering messages that really are like putting a candle to the dark, as Carl Sagan would say. We aren't sure what will work, when, or how much. But for all that uncertainty, that doesn't mean we shouldn't try.