The cybernetic difference between an organism such as a pollywog and an ecosystem such as a fresh-water bog is that an organism is tightly bound, and strict; an ecosystem is loosely bound, and lax.

Human health ultimately depends upon ecosystem products and services (such as availability of fresh water, food and fuel sources) which are requisite for good human health and productive livelihoods.

Talk of “ecosystem services” now draws attention to the helpful things that nature does unbidden, such as providing fresh soil and clean water.