Abstract
Some of the modern developments of concepts and ideas of Sir Arthur Tansley, one of the principal founders of the British Ecological Society, are discussed. These include the concept of the ecosystem: critical phases, quantitative studies of individual organisms in their natural ecosystems, evolution in ecosystems, and conservation of ecosystems and future prosperity. Mankind is considered as a lapidary with a sack of uncut diamonds, with limited resources, and able to cut only 1 diamond at a time. The job of the individual ecologist is to convince mankind to avoid finishing the sack overnight.