That cause which moves the humors in all the species of animate bodies against the natural course of their gravity moves the water through the earthly veins; and necessity draws it and abundance drives it out, and through the subtle passages it distributes it... And with careful solicitude it succours with it all the parts that are constrained by need of moisture. It is properly that which, through the earthly veins, moves the water infused within them and distributes it through the subtle passages. That cause which moves the humors in all the species of animate bodies against the natural course of their gravity is properly that which, through the earthly veins, moves the water enclosed within them and distributes it through the subtle passages. And as the low blood rises on high and pours out through the broken veins of the forehead, and as from the lower part of the vine the water climbs to its cut branches, so from the lowest depth of the sea the water rises to the summits of the mountains, where, finding its veins broken, it falls through them and returns to the low sea. Thus within and without it keeps varying, now rising with accidental motion and now descending with natural free motion. Thus, joined together in continual revolution, it keeps turning. Thus running here, there, up and down, no quiet ever rests it, neither in its course nor in its nature. It has nothing of its own but takes everything, and transmutes itself into as many varied natures as are the places through which it passes. Doing just as the mirror does, which takes into itself as many likenesses as are the things that pass before it, so this ever varies, now in site and now in colour, now including within itself new odours or flavours, now retaining new substances or qualities, now proving mortal or salutary. Sometimes it mixes with the air, or lets itself be drawn upward by heat, and when it reaches the cold region, where the heat, its guide, is constrained with it. And as the hand under water presses the sponge, whence the water that flees from it makes a wave amid the other water, so does the air that was mixed within the water; when that air is pressed by the cold, it flees with fury and drives out the other air; thus this is the cause of the wind. And as the hand which under water presses the sponge when it is well soaked, so that it constrains the enclosed water to flee, whence it penetrates by force among the rest, and the second water, which feels itself struck, departs with a wave from its place, so does the cloud ... Thus this, in the form of a cloud, presses the air, when the contrary cold constrains it, making with the air amid the air an undulation.

End. No accident so transmutes it that it does not, in the end, return to its nature.