Dissipation
Why order costs energy, and why living systems have to remain open in order to go on existing.
Dissipation refers to the throughflow and consumption of energy by which a system maintains its order. In order to remain ordered, a dissipative system must continually take in, convert and release energy.
At first sight this seems a paradox. According to the second law of thermodynamics, isolated systems tend of their own accord towards disorder. How, then, can a living being preserve its highly ordered form? The answer is that a living being is not an isolated system. Self-organisation does presuppose systems that are operationally closed (which in fact applies to all systems), but that are open to energy and stimulation. The throughflow and consumption of energy in such a thermodynamically open system is what we call dissipation. A candle flame, a whirlwind and a cell all owe their enduring form to a continual stream passing through them.
Staying open in order to exist
For psychology there is an illuminating analogy here, and we would stress that it is an analogy rather than a proof. A person maintains their psychological organisation not in isolation but through a continual exchange with their surroundings: contact, meaning, stimulation and rest. If that exchange falls away, it becomes harder to keep one's form. Conversely, a certain amount of energy, in the form of activation, motivation or involvement, is often a condition for a new order to arise.
The concept thus reminds us that there is nothing static about stability in living systems. What endures does so thanks to movement. A patient who is "stuck" is, in our impression, rarely standing still; more often a costly, energy-demanding order is maintaining itself with difficulty. Change then calls for different conditions, under which the energy can organise itself differently, rather than for more rest.