## Inertia v. motion

-Go up to the blank whiteboard and draw a rocket. The picture can’t tell the student where it is or whether it is moving or not. When we mathematize space the same thing happens. There is no place and no difference between motion and rest.

-An inertial motion clearly isn’t going anywhere, i.e. there is no definite place to which it tends. It also didn’t arise from any given place, since motion arising is a sort of acceleration, and inertial motion is not. Inertial motion is defined in abstraction from what makes motion finite, and so is infinite by definition.

-Inertial motion needs no cause of moving any more than resting stone needs a cause of continued inactivity. Though true, internal motion is defined in abstraction from its origin and terminus and  inertial rest is defined separately from any conditions that brought it about or will make it cease.

-Motion might be distinguished into causes in fieri and in esse where the coming to be of motion is acceleration. Inertia has no cause in fieri but inertia isn’t a sort of becoming since it is defined in abstraction from both its origin and its terminus.

-Aristotle defined motion by its terms, and it’s not clear that it is definable in any other way. Inertial motion has one element of motion but motions as such are from somewhere, to somewhere and inertial motions are not.

-One can see or experience something deserving the name inertial motion but it cannot be defined.

-The joke that “you’re not late till you get there” is true not just of being late but early, fast and slow , rightly directed or off target, or even having a direction at all. Inertia only has a direction from a counterfactual, sc. from a terminus that does not belong to it as inertial.