1. Nothing exists absolutely by itself; everything exists in relation with something else which is its "environment."
2. A thing and its environment cannot exist side by side for any considerable time without each affecting or influencing the other in some respects at least: a thing A and its environment B, which cannot but exist together, must needs act and re-act on each other.
3. The action and re-action of the thing A and its environment B on each other, brings about mutual adjustment, the fitting of each into the other.
4. According as this mutual adjustment or fitting is relatively complete or incomplete, there is Evolution or Dissolution, survival or extinction, of the thing (A) itself.[80]
5. The process of Evolution or Survival is characterized by:—
(a) Integration: grouping together of certain like units (such as atoms or molecules, living cells or individuals) into a whole,
(b) Differentiation: certain parts (or functions) of the aggregated whole becoming unlike each other or specialized, and
(c) Adjustment: fitting of the aggregated and differentiated whole into its environment.