Stability and Change
We live in a world where great incompatibles co-exist: the human scale and the superhuman scale, stability and mobility, permanence and change, identity and anonymity, comprehensibility and universality.
At first glance, stability and change seems like a simple concept. Some things change over time and others do not. Stability and change appear to be opposites. However, it is a little more complex than that. For example, the amount of water in a lake may appear not to change, but this is because the amount of water being removed from the lake is equal to the amount of water being added to the lake. What appears to be unchanging is actually changing the entire time, so the change brings about stability. "Dynamic equilibrium" is this type of stability created when things are constantly changing, but in balance with each other so the overall result is stable.
Time scales can also make a big difference in determining if something is stable or if it is changing. Mountains don't appear to be moving, yet if you look at them over longer periods of time, we know that mountains are growing and shrinking all the time. It is just happening so slowly that we can't see it directly. Over thousands of years, mountains vanish to weathering and erosion, and new mountains are created by volcanoes and the collision of tectonic plates. Mount Everest, the tallest mountain in the world, is growing about 2.4 inches a year. This means in the last 26,000 years, it has grown by an entire mile. Small changes become big changes over time, so something that may appear to be stable, may actually be changing.
This idea of stability and change is not so simple, which is why we must always consider what is going on at different scales, and in different time frames, in any system we are studying.
Another thing to consider when trying to understand stability and change is the scale at which you are viewing something. Changes may be so subtle that you don't see them, unless you look more closely, or from farther away. This is similar to looking at piles of snow in a snow drift. One pile of snow looks no different than any other pile. However, when you look at individual snowflakes, each one is unique; no two are alike. When a glass of water is heated from five to sixty degrees Celsius, it appears that nothing has changed. All seems stable. But when you look at the same glass of water at a molecular level, you will see the water molecules have sped up considerably with the addition of heat into the system. What seemed stable is actually changing quite a bit when looked at under a different scale.