In chapters titled Earth, Water, Air and Fire, Sagan touches on the oceans and atmosphere, the evolution of life on Earth, the laws of thermodynamics and human consciousness, always circling back to Lovelock's theories. Sagan is equally comfortable discussing scientists like Richard Dawkins and Lewis Thomas, and science fiction authors like Philip K. Dick and A.E. van Vogt. The chatty style and ranging mind communicate a broad understanding and should appeal to inquisitive readers who want to know more about Earth and our relationship with it. Copyright ? Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.