This thought provoking book covers details not discussed in many books about past life and past extinctions. Looking at the big picture of extinction, he provides insight to the nature of evolution, our past and possible futures. Using a skillful combination of specific data on individual mass die-offs and statistical examination of the entire history of life on this planet, he brings many difficult (or unpleasant) theories of extinction into focus. He analyzes many theories, from older standard views to the downright wacky, but eventually makes a strong case for celestial impacts as cause of many mass extinctions.