Ramon Margalef.
Perspectives in Ecological Theory.
University of Chicago Press. 1968
p36. Consider a river,
in which suspended organisms multiply. The water flows, carrying away organisms.
If the flow were perfectly laminar everything would he washed away and the water would become empty of life.
But flow is turbulent, and some organisms actually move against the main current;
others are carried away at a speed higher than the mean, and all, of course, multiply.
As a result, at a geographically fixed point a population is maintained in which increase
by multiplication compensates for the losses by drift, diffusion, and sinking.
The population has to be considered a process rather than a state ...
like a cloud that forms on one end and disappears at the other,
maintaining in between a form and a certain appearance of organization.