Apart from producing liquefaction and vaporization, heat has also the property of acting on physical matter so that its volume increases. Both facts are linked together by science through the thermodynamic conception of heat. As this conception firmly blocks the road to the recognition of the role of heat as the fourth state of matter, our first task will be to determine our own standpoint with regard to it. Further obstacles on our way are the so-called Laws of Conservation, which state that no matter and no energy - which for present-day science have become one and the same thing - can ever disappear into 'nothing' or come into being out of 'nothing'. This idea, also, will therefore require our early attention.²