Meteorology   

cannot be true of the sun; for if it were nourished like that, as they

say it is, we should obviously not only have a new sun every day, as

Heraclitus says, but a new sun every moment. Again, when the sun

causes the moisture to rise, this is like fire heating water. So, as

the fire is not fed by the water above it, it is absurd to suppose

that the sun feeds on that moisture, even if its heat made all the

water in the world evaporate. Again, it is absurd, considering the

number and size of the stars, that these thinkers should consider

the sun only and overlook the question how the rest of the heavenly

bodies subsist. Again, they are met by the same difficulty as those

who say that at first the earth itself was moist and the world round

the earth was warmed by the sun, and so air was generated and the

whole firmament grew, and the air caused winds and solstices. The

objection is that we always plainly see the water that has been

carried up coming down again. Even if the same amount does not come

back in a year or in a given country, yet in a certain period all that

has been carried up is returned. This implies that the celestial

bodies do not feed on it, and that we cannot distinguish between

some air which preserves its character once it is generated and some

other which is generated but becomes water again and so perishes; on

the contrary, all the moisture alike is dissolved and all of it

condensed back into water.

The drinkable, sweet water, then, is light and is all of it drawn

up: the salt water is heavy and remains behind, but not in its natural

place. For this is a question which has been sufficiently discussed (I

mean about the natural place that water, like the other elements, must

in reason have), and the answer is this. The place which we see the

sea filling is not its natural place but that of water. It seems to

belong to the sea because the weight of the salt water makes it remain

there, while the sweet, drinkable water which is light is carried

up. The same thing happens in animal bodies. Here, too, the food

when it enters the body is sweet, yet the residuum and dregs of liquid