lightness to the mobile: but downward motion results from the intrinsic heaviness of the mobile. </s>
<s id="id.5.0.22.00.03">Taking no account of the medium, all things will be moved downward.</s>
<s id="id.5.0.22.00.04">Upward motion takes place through extrusion by a heavy medium: as in the balance a less heavy thing is moved violently upward by a heavier one, so a mobile is extruded violently upward by a heavier medium. {1}</s>
</p>
</subchap2>
<subchap2>
<p>
<s id="id.5.0.23.00.00"/>
<s id="id.5.0.23.00.01">It is evident that the difficulty of cleaving the medium is not the cause why wood does not go down in water: for if [in this case] this difficulty were overcome by the form of the mobile, the wood would descend, if, for example, it was given the form of a cone or an arrow; and yet this floats no less than a flat board. </s>
</p>
</subchap2>
<subchap2>
<p>
<s id="id.5.0.24.00.00"/>
<s id="id.5.0.24.00.01">A fragment of Euclid proves that there exists a mathematical treatment of the heavy and the light. {1}</s>
</p>
</subchap2>
<subchap2>
<p>
<s id="id.5.0.25.00.00"/>
<s id="id.5.0.25.00.01">Telesio says that the cause of the acceleration of motion at the end is that matter accelerates motion because it is wearied of going down. {1}</s>
</p>
</subchap2>
<subchap2>
<p>
<s id="id.5.0.26.00.00"/>
<s id="id.5.0.26.00.01">It is proved that there exists no natural upward motion. {1}</s>
<s id="id.5.0.26.00.02">What is moved naturally, without hindrance, is moved toward a limit in which it is naturally at rest and from which it cannot back out of unless it be violently. </s>
<s id="id.5.0.26.00.03">Hence if wood goes up naturally in water, hence it it is moved to [a place] from which it will not recede except by force: but wood is carried without hindrance toward a limit which is near the surface of the water: hence from there it will not recede except by force. </s>
<s id="id.5.0.26.00.04">Which however is false; for if the water is removed from underneath it, the wood will retreat and descend naturally. </s>
<s id="id.5.0.26.00.05"> And do not tell me that the limit of the natural motion of wood upward is the surface of the water itself, and because of that, if the limit is moved, what was in it is [also] moved: for this is ridiculous. </s>
<s id="id.5.0.26.00.06">For the limit of natural motion is not some body, but must be something indivisible and immobile: now only the center is such a thing. </s>
<s id="id.5.0.26.00.07">Hence it is only towards the center that something is carried naturally; at which it naturally remains at rest, and from which </s>
