Everything is energy, even life ! Since the XVIIth century, humans have used this energy to satisfy their needs. We designed machines with more mechanical force and higher speed than us, we moved faster and faster and we increased our communications. We also learnt to store and transport that energy. In fact, we began with horses, we went further with sail-boats, our productions grew with steam in the XVIIIth century (one horsepower is equal to 740 Watt, that is to say 740 J per second) brought by coal burning, and then we drastically developed our industrial world with oil and electricity. Everywhere in the universe, energy comes from matter and from electromagnetic waves. Coal contains 25 millions of Joules per kg, oil -so easy to transport- 50 millions of Joules per litre and 1 gram of Uranium contains 3000 times more energy than 1 kg of coal ! Nowadays, we consume a lot of energy. Each of us permanently exploits "energetic slaves" ! Let me give you one proof... The power of a little car (Citroën C1) is 68 horses, that means 50 kW. So, the energy consumption of this C1 in one hour is 180 millions of Joules. We assume that the fuel consumption in one hour is 4 litres. We deduce that the cost of our "slave" is almost 8 euros. What would be the cost if we asked the same total enrgy to humans ? The average human power is 100 Watt. It is so necessary to have 68 x 740/100 workers to obtain the same power, that is 500 humans ! Even if we take the lowest salry in the world (near 0,04 euros in an african country), we reach a total of 20euros per hour ! Conclusion : the total energy provided by oil is cheaper than the energy provided by humans. The environmental and social consequences are dramatic... Maybe you are a little bit shocked by what I've said : the price of oil is too low ! If not, unemployment would be even bigger ! I don't think so ! Energy is in life, not in fossil fuels ! We could create wealth with our own energy and with the help of renewable energies, - slower - but with the same quality and with employment.