"Petrus Comestor saith that Mount Olympus riseth even to the clear aether, wherefore letters written in the dust on the summit of that mountain have been found unchanged after the lapse of a whole year. Neither can birds live there, by reason of the rarefaction of the air, nor could the Philosophers who have ascended it remain there even for a brief space of time, without sponges soaked in water, which they applied to their nostrils and sucked thence a denser air."