Water is a material of enormous paradox, among them the seeming contradiction between the fact that it is necessary for life yet is often valued so little that people use it as a convenient dumping ground. Many academic disciplines and professional practices focus on water-related issues, yet until fairly recently the subject of water itself was relegated to realms of science and engineering. Much, but not all, of the material in this section comes from those areas, but all make water central, rather than the human uses or attitudes toward water.