The ancient Greek philosopher Heraclitus stated: "Everything flows (changes). Nothing stays in place. — We both step and do not step into the same rivers, we are and we are not." Everything in the world is under constant change, either fast or very slow. The continental plates move a few millimeters or centimeters a year. When we look at their movement on a time scale of thousands or millions of years, we already start to see big changes. Other things change very quickly. A hurricane can destroy an entire big city in a few hours. In our environment (the world around us), there are constant changes in the ecology, landscape and physico-chemical conditions, we see these as environmental changes, such as deforestation, desertification or climate change. Some of these changes are very harmful and serious for people and other nature. Efforts must be made to control and prevent these changes, or one must be able to adapt to them. However, it is often not possible to completely prevent changes. "Everything flows." That's when adaptation is emphasized.

Like the environment, the society that interacts with it changes all the time: policies are replaced by others, old traditions disappear and new ones are born, new things are learned and new innovations are invented, etc. This is usually a positive thing. Society and the world are modeling wax and we can shape the world into what we want, more beautiful and happier, promote good values such as freedom, solidarity and equality. Create well-being with innovations. On the other hand, this malleability can be a bad thing: democratic and free Germany turned into a dystopian dictatorship and tyranny in an instant in the 1930s. So society can develop in both a good and a bad direction. Development is different from progress, it means a change in some direction, a trend. If society did not mold easily, we would not be able to adapt to current and future threats, we would not have resilience. That is why it is important that society has an open, free and democratic society with room for movement. However, we are not as free to make choices as we might like. Past choices limit our current and future possibilities.

In complexity theory, path dependence means that past choices (and laws, innovations, ways of thinking, policies and traditions, etc.) determine the present. If a large investment is made, for example an expensive and dangerous nuclear power plant is built, it will determine energy production far into the future. On the other hand, if we invest in wind power, it will be easier for us to get to a sustainable energy system faster. Past choices have a great influence on the present and the direction in which things develop. In society, for example, laws enacted have a strong influence on what kind of changes are possible.

If you take a train towards the north from a train station with several crossing tracks, it is easy to change direction and track at the beginning. In this case, there are several possible futures. When the train is moving along the tracks, however, it will soon be very difficult to change direction. Once we start down a certain path, it can be difficult or even impossible to change direction. However, there are so-called bifurcation points where new opportunities open up and the direction can be changed. So even big social changes are possible. So we are not doomed because of the bad choices we made. However, it is good to be aware of the ballast of the past and how difficult it is sometimes to bring about change. In the long term, however, the changes can be huge. If you make one change (0.1) every day 1.1^30=17.5 the change in 30 days is huge, while if you do nothing 1^30=1 then nothing changes. Conservatism is often harmful when you want to keep everything the same. Then the bad things like inequality, slavery, witch hunts, suppression of women's and gay rights, economic inequality and ignorance will stay the same and nothing will get better. That's why liberalism is better. Then things can really change. Of course, there are also many things worth preserving and we can preserve the wisdom of past generations. However, it is important to realize that the world is not ready and that things were often worse before. 123 years ago, in 1900, women were not allowed to vote and the indigenous people of Africa had no human rights. Social change is made possible by a democratic system, otherwise change is not possible. However, even democracy must not be a dictatorship of the majority, that is why wisdom and experts, bureaucracy are needed.

Sustainability is often a matter of preserving something good, for example an old forest or cultural heritage. However, the world cannot be completely controlled or stopped. Therefore, it is necessary to accept that things also change. What we can greatly influence is that the current state of affairs would be as good as possible and that people and other nature could do as well as possible, that we have ecosystems and ecosystem services that function as well as possible, that society would have as much resilience as possible and that people would be as happy and well-being as possible, that we can reduce suffering. We can cherish all that is good and beautiful as long as we have them. Nothing beautiful and good will ever disappear, the fact that they once were and brought joy. They will remain in the pages of history forever. From this we can also gain a new understanding of the significance of things. Every thing that was once important to someone is meaningful, and that meaning cannot be taken away. Every good deed we do matters to someone, somewhere. What a beautiful thought. Thinking about the purpose of life is often difficult. Is it happiness, a fight for good, or do we define it ourselves? It is easier to determine relevance, the fact that something has once been important to someone. When you understand the meaning and find things that are important and meaningful, notice how joy springs from this thought.

The deepest essence of sustainability science and sustainable development is this: to protect what is important to us. Prevents harmful changes and changes for the better what is bad, preserving what is valuable. Everything in the world gets its meaning only when there is someone giving it meaning. So this requires a subject. Values make the world valuable and this requires someone to give value. Values are sometimes subjective or relative, but often also objective. The Finnish philosopher G.H. von Wright's language reflects reality like a mirror, as does mathematics. Therefore, if we can use language to justify the importance and goodness or badness of something, then this is a logical and valid argument. Goodness is something that brings something more, something good that produces happiness and well-being, such as health, knowledge, sports or music. Bad things take away good things, such as sickness, poverty or suffering.

Progress is the advance of good things, good development. Sustainable development is exactly this kind of good development. Sustainable development fits within the limits of the planet, it nurtures what is good and meets people's needs, promoting happiness and genuine well-being. In terms of human development, the most important thing is learning new things, the development of science and art. Knowledge is power and its light leads humanity on a good path. Knowledge combined with values is wisdom. One of the highest goals in human life is to achieve wisdom. Wisdom leads nations to the light from the night of ignorance and misery.