**1. Introduction**

"Business as usual" will not lead us into a sustainable future. Therefore, we need visions about alternative routes to follow. We have to think along new lines, both collectively and personally, in order to make other choices and to reconsider what is really important. Such alternative, sustainable thinking is already underway, and when we analyse it, we discover that a gradual creation of new concepts is important. New concepts open new perspectives and allow for fruitful discussions. However, new concepts have to be precise enough. Twenty-five years ago, the concept of "sustainable development" achieved global consensus [1], and initiated waves of new thinking. As we shall see, there was also a great need to discuss the concept itself, and to refine purpose and aims through a number of sub-concepts. This process is still going on. For instance, it is not yet clear what should be meant by "green economy". In the following, we shall also illustrate how conceptual progress in certain academic disciplines has fuelled our thinking about environmental questions.

A significant element in sustainable thinking is our personal attitudes. Good concepts help us in the process of developing well-founded attitudes. We shall consider the development of attitudes as a process of systematic thinking. Our perseverance in environmental work depends highly on the quality and strength of personal attitudes.

Given a good conceptual framework and well-founded attitudes, we should probably be well armed to fight for a sustainable future? In addition, rhetoric, or the way you communicate, should not be underestimated. We are reminded by the famous Roman speaker Cicero (106-43 BC), that the way you present and formulate your message is crucial; also in environmental questions, rhetoric matters. In fact, concepts and rhetoric are not always clearly separated. The

formulation "Think globally and act locally" is both good rhetoric and contains a conceptual core about how we all can participate to solve common challenges. In a separate section, examples of well-formulated statements from various authors will be cited.

After having illustrated the importance of concepts, attitudes and rhetoric in order to shape environmental action, the problem of mental barriers will be discussed. We have all an ability to suppress, or deny, environmental threats. This psychological mechanism supports "busi‐ ness as usual". The book "Collapse – how societies choose to fail or succeed" warns us about this psychological trap [2].

An important product of sustainable thinking should be to create hope. Concepts, attitudes and rhetoric are helpful not only to describe problems, but also to show possibilities. This will be discussed in a final section.
