The Gaia hypothesis, which promulgates the idea that the Earth as a whole is alive, is discussed. The microworld and the idea that symbiosis is a major force behind evolution are emphasized. (KR)

Reviews seismological studies that provide evidence of the existence of continental roots beneath the continents. Suggests, that through the collisions of plate tectonics, continents stabilized part of the mobile mantle rock beneath them to form deep roots. (ML)