Book,  Paragraph

 1   I,  2 |     circular motion, while the upward and downward movements are
 2   I,  2 |       are in a straight line, "upward" meaning motion away from
 3   I,  2 |     has a single contrary; and upward and downward motion are
 4   I,  2 |       if the natural motion is upward, it will be fire or air,
 5   I,  2 |    bodies-fire moving straight upward and earthy bodies straight
 6   I,  2 | instance, is the case with the upward and downward movements,
 7   I,  3 |       of everything that moves upward. Now, necessarily, everything
 8   I,  3 |        which is unnatural, the upward movement will be natural;
 9   I,  3 |      natural; and if it is the upward which is unnatural, the
10   I,  3 |   forced violently aside in an upward or downward direction. For
11   I,  6 |       can be infinite. For the upward and downward motions are
12   I,  7 |    reasoning, that which moves upward, can prolong its movement
13   I,  8 |        the slower would be the upward or downward movement; but
14  II,  2 |        fire, for example, only upward, and earth only to the centre.
15  II,  5 |  course possible, and, just as upward movement is the superior
16  II,  13|    natural to it. Will this be upward motion or downward or what?
17  II,  13|       have some motion; and if upward and downward motion are
18  II,  13|     the earth does not prevent upward movement, then no more could
19  II,  13|     Why, again, does fire move upward? Not, surely, because of
20  II,  13|       its indifference. Motion upward and downward and sideways
21  II,  14| forcibly thrown quite straight upward return to the point from
22 III,  2 |        thus qua light produces upward motion, being propelled
23 III,  5 | greater, moves faster with the upward motion which belongs to
24 III,  8 |  movement of fire, which is an upward and rectilinear movement,
25  IV,  1 |    away from the centre I call upward movement and that which
26  IV,  1 |       we mean that which moves upward or to the extremity, and
27  IV,  2 |      is always light and moves upward, while earth and all earthy
28  IV,  2 |    which disposes fire to move upward. If it were, the greater
29  IV,  2 |    mass is and the quicker its upward movement: and, similarly,
30  IV,  2 |      the more readily it moves upward, and any portion of air
31  IV,  2 |      other words why some move upward and others downward. The
32  IV,  2 |  constantly as the other moves upward. But that cannot be so,
33  IV,  2 |      of solid to void, but the upward movement of the greater
34  IV,  2 |   absurdity in attributing the upward movement of bodies to a
35  IV,  2 |       nature of a void to move upward and of a plenum to move
36  IV,  2 |        and nothing which moves upward (except as being passed
37  IV,  3 |      move always and naturally upward and others downward, while
38  IV,  3 |   while others again move both upward and downward. After that
39  IV,  3 |       Now, that which produces upward and downward movement is
40  IV,  3 |        of all things that move upward or downward is the extremity
41  IV,  3 |     Thus to ask why fire moves upward and earth downward is the
42  IV,  3 |      place, a light thing goes upward, a heavy thing downward.
43  IV,  4 |        external obstacle moves upward, and earth downward; and,
44  IV,  4 |        own nature always moves upward, by absolutely heavy one
45  IV,  4 |        we observe fire to move upward even in air itself, while
46  IV,  4 |    another. Secondly, like the upward movement of fire, the downward
47  IV,  5 |      is light and always moves upward, while a thing which has
48  IV,  5 |   absolutely, possess both the upward and the downward motion.
49  IV,  5 |      removed, it will not move upward to the place of fire, except
50  IV,  5 |      may be drawn up, when the upward movement of air which has
51  IV,  5 |     water. Nor does water move upward to the place of air, except
52  IV,  5 |         As earth fails to move upward, so fire fails to move downward
53  IV,  5 |    either all things will move upward or all things will move
54  IV,  5 |    shown that the downward and upward movements are equally constant
55  IV,  5 | similar, which moves uniformly upward, there will be nothing to
56  IV,  5 |  plenum. Fire, then, as moving upward, will be void, earth, as
57  IV,  5 |      excel a little air in the upward movement and air excel water
58  IV,  6 |       account for their moving upward or downward in general,
59  IV,  6 |      drive the movement of the upward moving bodies) is not uniform