The mistakenness of the opinion that the fire is stored up in the 1 clouds may be inferred from many considerations. For example, if the fire merely falls from the sky, why does it not do so every day from the glowing mass that is constantly up there? Then, again, the theory gives no explanation of the downward course of the fire, an element which naturally rises. Fires on earth from which embers fall belong to a different category; the embers possess a certain amount of weight, which carries them down. Fire cannot descend in the same way, but must be forced or conducted down. Nothing analogous to a terrestrial fire 2 can take place in that pure ethereal fire which contains nothing that can carry it down to earth. Otherwise, if any portion of it fall down, the whole is endangered; for anything susceptible of gradual diminution piecemeal may evidently also fall in a mass. Besides, if an element whose lightness habitually prevents its fall contain any weight in its hidden depths, how could it maintain itself in the place whence it fell? But, it is urged, are not certain forms of fire wont to descend into the lower parts of air very much like these bolts of lightning that we are investigating? Admitted. Only they are conveyed, they do 3 not proceed of themselves. Some force not resident in the ether carries them down. For in the ether no violent compulsion, no breach, no interruption of the wonted continuity, can occur. It preserves a fixed succession; its fire cleansed of impurity claims the upper regions as its own, and performs its functions in preservation of the universe with beautiful precision. It cannot leave its place, no, nor even be thrust from it by external force, because no disturbing body can find lodgment in ether. Its fixed and ordered composition renders conflict impossible. XIV