410 through it, with the medium unmoved (nor does it do anything to the sound, even if the medium were moved; for no matter how strong the wind is blowing the bell is silent); the sound in the bell is progressively weakened, and by itself it returns to silence.
And just as heat as well is impressed in a more penetrating way in dense and very cold matter, like iron, than in matter which is rare and less cold, even if both of them become warm through the same heat, so a heavier thing is sometimes moved more, farther, and more swiftly by the same force.
It must not be said that in the bell it is the air which sounds: indeed this is the saying of fools; for the sound of different bells would be the same, and a wooden or leaden bell would sound just as would a bronze one.
There is a threefold classification of motion: first, with respect to spaces: thus, one straight, another circular: another, with respect to points of arrival; thus one upward, another downward: a third, with respect to primary efficient causes; thus, one natural, another violent.
Aristotle, in Book III of <i>De Caelo</i>, text #27 [301b1-4], asserts that things that are moved must be either heavy or light; for if they were neither heavy nor light, when moved by force they would be moved without end: and in the following text [301b23-27]{my notes} he says that air helps both motions, namely upward and downward, and that projectiles are carried by the medium: hence if the medium air, impelled by force, is moved without end, since it is neither heavy nor light, it will carry projectiles without end.
Philoponus, Avempace, Avicenna, the divine Thomas, Duns Scotus, and others, who try to defend [the view that] motion in a void takes place in time, do not proceed well by assuming in the mobile a double resistance, one, namely, accidental, stemming from the medium, the other intrinsic, from the proper heaviness. For these two resistances are but one, as is evident; for the same medium both resists a heavier thing more, and makes a mobile lighter. {1}
AverroÂs, in his Commentary on <i>De Caelo</i>, Book I, text #32 says {1} that a sphere is not physically tangent at a point.