On the Force of Percussion

JOH. AL. BORELLI

it has such a connection with the time in which it is transacted, that regarding motion itself, nothing exists in act other than an indivisible moment in the instant of the present time, actively vigorous and operating. Just as the past parts of time do not exist, nor the future, so too the past parts of a migration or local transition—which is a certain operation—namely, transactions already completed, or those yet to be, do not exist. Unless, perhaps, one wishes to posit and recognize the space traversed in the excursion of said motion as the existence of the motion itself—which is not fair, for the operation of motion, which is consumed in the space traversed, does not exist all at once, but runs through the length of the space successively according to the flow of time. Therefore, the space traversed can be rationally compared with the quantity of time, which is measured successively by its flow.

That motion is of the genus of quantity is evident from the primary passion of quantity, for whatever things admit of "more" and "less"—namely, those that can be increased infinitely and likewise diminished at will—are entirely quantities. But according to the partition or augmentation of the time in which motion is effected, the migration or successive transition also subdivides or grows; therefore, it will be of the genus of fluent quantity.

But although motion cannot be understood without the flow of time, and they are so linked that one cannot exist without the other, there are nevertheless some differences by which they are distinguished. Time is always of the same species, for there is no time that differs from another time in velocity or slowness; it is only diminished or increased through its own extension, just as the simple length of a straight line does not differ from another straight line in species, but only in measure. However, in motion there is "more" and "less," not only extensively, as they say, but intensively; namely, two unequal transitions or motions can occur in the same time, insofar as a greater space is traversed in one than in the other. In that case, the first motion will be called fast, and the second slow. Here it is clear that a fast motion is truly greater than a slow motion, not in extensive quantity, but in intensive strength and energy, so to speak.

The force of velocity is called impetus.Therefore, in motion itself, insofar as its intension is considered, that force and energy of velocity with which a body is moved ought to be conceived, which, in summary...