Book,  Paragraph

 1   I,  7 | rectilinear movement is natural or constrained, in either case the force
 2   I,  8 |     constraint or extrusion; for a constrained movement always diminishes
 3  II,  1 |          natural to itself. Such a constrained movement would necessarily
 4  II,  13|       there is no natural but only constrained movement. Seeing, however,
 5  II,  13|          natural movement, have no constrained movement; and where there
 6  II,  13|         there is no natural and no constrained movement there will be no
 7  II,  13|     movement, is either natural or constrained. But if there is any natural
 8  II,  13|    together at the centre was also constrained. (The form of causation
 9  II,  13|         movement to the centre was constrained, and its rest at the centre
10  II,  14|           from it, must needs be a constrained motion. It cannot be the
11  II,  14|           the centre. Being, then, constrained and unnatural, the movement
12 III,  2 |        move by constraint: and the constrained is the same as the unnatural.
13 III,  2 |         Rest, also, must either be constrained or natural, constrained
14 III,  2 |            constrained or natural, constrained in a place to which movement
15 III,  2 |        place to which movement was constrained, natural in a place movement
16 III,  2 |            other hand, its rest is constrained, what is hindering its motion?
17 III,  2 |           the various elements are constrained by one another to move as
18 III,  2 |         natural movement which the constrained contravenes, and the prime
19 III,  2 |     natural movement, which is not constrained or contrary to its nature.
20 III,  2 |  constraint, and must continue its constrained movement infinitely. For
21 III,  2 |        endowed with this function, constrained movement would be impossible.