“Until recently, ecologists were content to describe how nature “looks” (sometimes by means of fantastic terms!) and to speculate on what she might have looked like in the past or may look like in the future. Now, an equal emphasis is being placed on what nature ‘does’, and rightly so, because the changing face of nature can never be understood unless her metabolism is also studied. This change in approach brings the small organisms into perspective with the large, and encourages the use of experimental methods to supplement the analytic. It is evident that so long as a purely descriptive viewpoint is maintained, there is very little in common between such structurally diverse organisms as sperma-tophytes, vertebrates and bacteria. In real life, however, all these are intimately linked functionally in ecological systems, according to well-defined laws. Thus the only kind of general ecology is that which I call a ‘functional ecology’, and this kind is of the greatest interest to all students of the subject, regardless of present or future specialisations.”

Eugene Odum (1957) Fundamentals of Ecology. p. ix, cited in: Edward Goldsmith (1970-73/2013) Towards a Unified Science http://www.edwardgoldsmith.org/598/