Book,  Paragraph

  1   I,  2 |             our starting-point. All natural bodies and magnitudes we
  2   I,  2 |             is one sort of movement natural to each of the simple bodies.
  3   I,  2 |     movement is the contrary of the natural and a thing can have no
  4   I,  2 |             unnatural, if it is not natural, to the body moved. If then (
  5   I,  2 |             some other element, its natural motion must be the contrary
  6   I,  2 |          some other motion which is natural to it. But this cannot be.
  7   I,  2 |          this cannot be. For if the natural motion is upward, it will
  8   I,  2 |         that all movement is either natural or unnatural, and that the
  9   I,  2 |            unnatural to one body is natural to another-as, for instance,
 10   I,  2 |       downward movements, which are natural and unnatural to fire and
 11   I,  2 |             to these bodies, is the natural movement of some other.
 12   I,  2 |          hand, circular movement is natural to something, it must surely
 13   I,  2 |             ordained to move with a natural circular motion, as fire
 14   I,  3 |             upward movement will be natural; and if it is the upward
 15   I,  3 |     unnatural, the downward will be natural. For we decided that of
 16   I,  3 |         anything, the other will be natural to it. But since the natural
 17   I,  3 |        natural to it. But since the natural movement of the whole and
 18   I,  3 |      changes of properties. But all natural bodies which change their
 19   I,  7 |     movements are finite, and every natural body must always have its
 20   I,  7 |     constraint, it possesses also a natural motion, that is to say,
 21   I,  7 |        itself to be the goal of its natural movement and another, equally
 22   I,  7 |             rectilinear movement is natural or constrained, in either
 23   I,  7 |            unnaturally, must be the natural place for some other body,
 24   I,  8 |         constraint, its contrary is natural. If, then, it is by constraint
 25   I,  8 |          from here to there will be natural, and if earth from there
 26   I,  8 |             movement hither will be natural. And the natural movement
 27   I,  8 |            will be natural. And the natural movement in each case is
 28   I,  8 |             for a body which has no natural movement at all cannot be
 29   I,  8 |           If then the bodies have a natural movement, the movement of
 30   I,  8 |  starting-point and the goal of the natural movement must differ in
 31   I,  8 |             for it would have to be natural to something else, and there
 32   I,  9 |          that it is composed of all natural perceptible body.~First,
 33   I,  9 | circumference of the whole, or that natural body whose place is at the
 34   I,  9 |           heaven. For if there is a natural body outside the extreme
 35   I,  9 |             position must be either natural or unnatural. But it cannot
 36   I,  9 |          the exterior place will be natural to some other body, since
 37   I,  9 |       unnatural to one body must be natural to another: but we saw that
 38   I,  9 |        matter, which is, as we saw, natural perceptible body. So that
 39   I,  9 |     movement. But in the absence of natural body there is no movement,
 40   I,  9 |       creature, outside of which no natural development can fall, has
 41   I,  10|         destructible like any other natural formation. Others again,
 42   I,  12|            things which compose the natural body are the very same that
 43  II,  1 |            some other movement more natural to itself. Such a constrained
 44  II,  1 |            on the first body, whose natural motion is different, and
 45  II,  3 |            do so only if the body’s natural movement were towards the
 46  II,  3 |            the circular movement is natural, since otherwise it could
 47  II,  3 |      unnatural is subsequent to the natural, being a derangement of
 48  II,  3 |          being a derangement of the natural which occurs in the course
 49  II,  4 |           their numbers, it is most natural to arrange them in this
 50  II,  6 |      between the two; and we expect natural motion to reach its maximum
 51  II,  6 |     unnatural endure as long as the natural, or any form of incapacity
 52  II,  7 |         movements. It would be most natural and consequent upon what
 53  II,  7 |           there is an element whose natural movement is circular. In
 54  II,  8 |           no place in that which is natural, and what happens everywhere
 55  II,  8 |             of the larger circle is natural when all the circles are
 56  II,  8 |           themselves forward, it is natural that both should be spherical-a
 57  II,  12|        appear surprising. For it is natural that the best-conditioned
 58  II,  12|      regarding the arrangement as a natural one. In thinking of the
 59  II,  12|            fact, has its particular natural motion, to which the general
 60  II,  13|            that of the thing or the natural centre. But it is better
 61  II,  13|        outset whether bodies have a natural movement or not, whether
 62  II,  13|            not, whether there is no natural but only constrained movement.
 63  II,  13|       Bodies, we say, which have no natural movement, have no constrained
 64  II,  13|     movement; and where there is no natural and no constrained movement
 65  II,  13|            like movement, is either natural or constrained. But if there
 66  II,  13|    constrained. But if there is any natural movement, constraint will
 67  II,  13|          downward movement which is natural to it.) But suppose both
 68  II,  13|             be some motion which is natural to it. Will this be upward
 69  II,  13|       manner and direction of their natural movements? In the infinite
 70  II,  13|             If the extremity is the natural place of fire, clearly earth
 71  II,  13|      clearly earth must also have a natural place. But suppose that
 72  II,  13|             the centre had been its natural place.~We have now outlined
 73  II,  14|             the earth.~Further, the natural movement of the earth, part
 74  II,  14|            the way that some of the natural philosophers describe. Only
 75  II,  14|         parallel. This would be the natural form of movement towards
 76 III,  1 |             Now things that we call natural are either substances or
 77 III,  1 |       nature concerns bodies: for a natural substance is either a body
 78 III,  1 |        analysis of the character of natural things, and equally from
 79 III,  1 |          his circle by the earliest natural philosophers. But what these
 80 III,  1 |     impossible. But with respect to natural bodies there are impossibilities
 81 III,  1 |          nature out of numbers. For natural bodies are manifestly endowed
 82 III,  2 |         simple bodies should have a natural movement may be shown as
 83 III,  2 |    unnatural movement presupposes a natural movement which it contravenes,
 84 III,  2 |            either be constrained or natural, constrained in a place
 85 III,  2 |           movement was constrained, natural in a place movement to which
 86 III,  2 |         place movement to which was natural. Now manifestly there is
 87 III,  2 |        centre. If then this rest is natural to it, clearly motion to
 88 III,  2 |             motion to this place is natural to it. If, on the other
 89 III,  2 |     constraint but naturally. But a natural rest proves a natural movement
 90 III,  2 |             a natural rest proves a natural movement to the place of
 91 III,  2 |           kind of movement which is natural to them. For if the various
 92 III,  2 |              each must still have a natural movement which the constrained
 93 III,  2 |             If there is no ultimate natural cause of movement and each
 94 III,  2 |           And if their movement was natural, a moment's consideration
 95 III,  2 |         motion in virtue of its own natural movement, and the other
 96 III,  2 |           position that disorder is natural, and order or system unnatural.
 97 III,  2 |            system unnatural. But no natural fact can originate in chance.
 98 III,  2 |             that every body has its natural movement, which is not constrained
 99 III,  2 |            moved thing which has no natural impetus cannot move either
100 III,  2 |       constraint, movement which is natural, as downward movement is
101 III,  2 |        would be impossible. And the natural movement of a body may be
102 III,  3 |             thing.) But since every natural body has it proper movement,
103 III,  4 |            faces, or that any other natural conformation is composed
104 III,  5 |           fire will be first in the natural order. And whether the finest
105 III,  5 |            that they allow only one natural movement, which is the same
106 III,  5 |        matter of observation that a natural body possesses a principle
107 III,  5 |       established of a plurality of natural movements, it is impossible
108 III,  8 |      function, and power; for every natural body has, we maintain, its
109  IV,  1 |           other in the speed of its natural downward movement.~
110  IV,  3 |         that the place which is the natural goal of the movement of