288 is to be thought more light than heavy. But this is the only thing I would conclude by their manner of arguing; if it is a good manner, let them see for themselves what is concluded: as for myself however I would say that the elements in their own places are neither heavy nor light.For if a portion of water in water were heavy, it would go down; which it does not: and if it were heavy, how, swimming in the deep, would we not feel the heaviness of such a vast size of water? To this they would answer: because the parts of water adhere to the parts below, as the bricks of the wall lean on the bricks below; whence, they say, it happens that the mouse which lives in a wall does not feel the weight of the stones. {1}As a matter of fact this comparison does not seem quite appropriate. For first they compare fluid and falling water to a solid and fixed wall: then, there is a sign that the bricks do not sit on the mouse's shoulder in that, when the mouse is taken away, the hole where the mouse was remains, and the bricks do not fall in it; but, when a fish or a man is taken out of water, the place where the man was does not remain, but is immediately filled with water, which indicates that water rests on the fish or the men. How, then, is the problem to be untangled, if not by our saying that water and air do not exert weight in their own regions? So that the whole explanation of the problem is as follows: we are said to be weighed down, when a certain weight which tends downward by its heaviness rests on us, and we need to resist by our force in order that it does not go down any further; now this resisting is what we call being weighed down.But since it has been demonstrated {1}, that bodies heavier than water, let down into water, go down, and are, indeed, heavy in water, but less heavy than in air; and it has been shown that things lighter than water, impelled by force under water, are raised upward; but that those that are equally as heavy as water are carried neither upward nor downward, but stay where they are placed, provided that they are completely under water; from this it is evident that if when we are under water a certain body heavier than water leans on us, such as a stone, we will indeed be weighed down, but less than if we were in air, since the stone in water is less heavy than in air: but if, staying in water, a body lighter than water is fastened to us, not only would we not be weighed down, but we would even be raised by it; as it is evident when swimming with a gourd, even though otherwise, being in air, we are weighed down by the gourd; this is because the gourd impelled into water is carried upward and lifts, but in air it is carried downward and exerts weight: now if when we are in water a certain body equally heavy with water hangs over us, we will not
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