Both the living system and the medium change in congruence with one another. They change their structure / shape so that they fit together in a drift. The concept of drift does not imply a chaotic situation because it is being determined on a moment- to-moment basis by the interactions. The path of drift is contingent upon the interactions. So unilateral steering is an illusion. This path of drift is a path without any choices. It is a path of conservation of (a) the organisation of the living system and (b) of congruence with the medium. This is the paradigm for survival.