The line of consideration pursued in the last part of this chapter has led us from certain observations in the plant kingdom, concerning the coming into being of ponderable matter from 'nothing', to a corresponding picture of the earth's meteorological sphere. When discussing the plant in this respect we found as an instance 'worth a thousand, bearing all within itself the case of Tillandsia and more particularly the surprising appearance of phosphorus in it. Now, in the meteorological realm it is once more phosphorus which gives us an instance of this kind. For there is the well-known fact of the presence of phosphorus in conspicuous quantities in snow without a source being traceable in the atmosphere whence this substance can have originated in ponderable condition. The phosphorus appearing in snow, therefore, brings before our very eyes the fact that the heights of the atmosphere are a realm of procreation of matter. (In our next chapter we shall learn what it is in phosphorus that makes it play this particular role in both fields of nature. What interests us in the present context is the fact itself.) * The knowledge we have now gained concerning the disappearance and appearance of physical water in the heights of the atmosphere will enable us to shake off one of the most characteristic errors to which the onlooker-consciousness has succumbed in its estimation of nature. This is the interpretation of thunderstorms, and particularly of lightning, which has held sway since the days of Benjamin Franklin. Before developing our own picture of a thunderstorm let us recognize that science has found it necessary to reverse the explanation so long in Vogue. Whereas it was formerly taken for granted - and the assumption was supposed to rest upon experimental proof - that the condensing of atmospheric vapour which accompanied lightning was the consequence of a release of electrical tension by the lightning, the view now held is that the electrical tension responsible for the occurrence of lightning is itself the effect of a sudden condensing process of atmospheric moisture.