Energy determines our lives. Without energy, plants, animals and humans would not be able to live. Without energy, there would be no movement. But what is energy? Where does it come from and how is it used – yesterday, today, tomorrow? The DVD provides an illustrative introduction into the highly topical issue of energy. Starting with the human perception, it leads us to the cosmic primal source, the huge fusion power plant above our heads – to the sun. In doing so, it explains how energy reaches the Earth and is used here in different ways by plants, animals and humans. The physics part clears up the terms work, power and degree of efficiency. The DVD shows what conversion losses occur in the process from primary energy to useful energy, of course including the clarification that energy can neither be generated nor lost in a physical sense. The ecological, economic and social sustainability is discussed. This way, it is made clear that only Renewable Energy – thus energy from the Sun – can secure our future.