be weighed down by it nor will we be raised, since such a body will be carried neither upward nor downward. </s>
<s id="id.1.1.11.06.15">But no body can be found which is more equal to water in heaviness than water itself: it is therefore not astonishing if water in water does not go down and does not exert weight; for we have said that to be weighed down means to resist with our force a body that is inclining downward. </s>
<s id="id.1.1.11.06.16"> And exactly the same reasoning should be used concerning air. </s>
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<s id="id.1.1.11.07.01">This, in my judgment, whatever others may say, is the true explication of the problem. </s>
<s id="id.1.1.11.07.02">Therefore, since neither air nor water in their own regions is carried downward or upward, they are not to be called either heavy or light; since heavy things may be defined to be those that are carried downward, and light things those that are carried upward. </s>
<s id="id.1.1.11.07.03">And when we speak of motion, one must always take account not only of the heaviness or the lightness of the mobile, but also of the heaviness and the lightness of the medium: a heavy thing will not be moved downward, unless it will be heavier than the medium through which it must be carried; and a light thing will not go up, unless it is lighter than the medium through which it is moved. </s>
<s id="id.1.1.11.07.04">This being so, water will not go down in water, since water is not heavier than water; and since it does not go down, water will not be heavy in water. </s>
<s id="id.1.1.11.07.05">Now if it is asked, not as Aristotle considered them, but in themselves, purely and simply and absolutely, regardless of anything else, whether the elements are heavy, we answer that, not only water or earth or air, but also fire, and whatever is lighter than fire, have heaviness, and in short all things that have quantity and matter linked with their substance. </s>
<s id="id.1.1.11.07.06">But since Aristotle says the contrary of this, assuming something purely and simply light which nowhere exerts weight, we judge that such an opinion must be examined: which is what we will develop in the next chapter. </s>
