The movement carried out by a projecting subject is nothing else than a passage occurring in a well-determined time, or rather a velocity which by its nature involves a passage or migration. Therefore, it is obvious that, if all the external causes impeding and slowing down this passage and movement are removed, the movement will last for ever, as long as the effect of any cause cannot by itself fail or soften without addition of opposite causes which weaken or destroy it. Similarly, no other quality or accidental property can be destroyed or weakened spontaneously by itself if the subject in which it is present continues and never stops (in the light of nature, it appears that beings cannot change into nothing spontaneously if the continuous inflow of God three times the greatest is not missing or subtracted, influx which we believe the creatures need) and if, besides, no internal or external causes destroying this quality occur. Similarly, the figure of a wooden triangle would never disappear if the material, the wood, of which it is made could be eternal. It could never be destroyed by another external cause. In the same way, this quality by which bodies move from one place to another would never disappear if the body in which it is present and which migrates could be eternal and if its movement was not weakened or destroyed by any opposite cause.