Sir Arthur Tansley (1871–1955), an English botanist, coined the term ecosystem in 1935. In order to appreciate the concept denominated by the word, it is useful to know a little about Tansley as a person and the context in which he worked. I think it is fair to say that Tansley was the father of modern British plant ecology. He was one of the founders of the British Ecological Society, the world’s first ecological society, the founder of the journal The New Phytologist, an editor of The Journal of Ecology from 1916 to 1936, the author of several authoritative books on British vegetation, a gifted teacher with several textbooks on plant ecology, a student of Sigmund Freud and author of a successful interpretive work titled The New Psychology, and a conservation advocate who helped establish the Nature Conservancy of the United Kingdom. These few remarks, based on long accounts of Tansley by Godwin (1977) and Evans (1976), suggest something of his character. Tansley was a scientist with broad interests, with a deep understanding and appreciation of field botany, and a special concern about philosophy and the processes of thought and research methodology. In addition to botany, he had a background in geology.