• • • John Harper • • • Nature conservation has changed from an idealistic philosophy to a serious technology. Ecology, the science that underpins the technol­ ogy of conservation, is still too immature to provide all the wisdom that it must. It is arguable that the desire to conserve nature will in itself force the discipline of ecology to identify fundamental prob­ lems in its scientific goals and methods. In return, ecologists may be able to offer some insights that make conservation more practicable (Harper 1987). The idea that nature (species or communities) is worth preserv­ ing rests on several fundamental arguments, particularly the argu­ ment of nostalgia and the argument of human benefit and need. Nostalgia, of course, is a powerful emotion. With some notable ex­ ceptions, there is usually a feeling of dismay at a change in the sta­ tus quo, whether it be the loss of a place in the country for walking or rambling, the loss of a painting or architectural monument, or that one will never again have the chance to see a particular species of bird or plant.