The ponderous motions are of 3 natures; the 2 are contrary and the third partakes of the one and the other. The reason is that the motion made from low to high, the more it rises, the weaker it becomes. The other, on the contrary, in falling, the more it lowers, the more it grows. If the first leaves its last contact without any injury, the second, on the contrary, finds its own with great detriment to itself and to the other part. The third motion will be transverse, which up to the middle resembles the weight that descends, and from the middle to the end resembles the weight that rises. // The transverse motion up to the middle holds the nature of the weight that falls, and because up to that term its weight grows, from the middle onward, weakening, it leaves the straight course and, twisting downward, takes on the nature of the second, which rises. // Because every middle partakes of the nature of the extremes, I say that the movement that descends, if it is one pound, at mid-way will be 2, at the end 3; and it receives as much blow as it gives at its last contact.

...partakes of the 2 seconds. The reason that the 2 ... a weight on high, the contact of the last ascent does not suffer any detriment. The second, when it will be thrown from high to low, its last contact receives great detriment. The one, the more it moves away from its cause, the weaker it becomes, and the other, on the contrary, the stronger it becomes. The third, transverse motion, grows up to the half of the way, and up to here resembles the blow of the weight that descends, and from the middle of the way onward, weakening, it takes on the nature of the motion that rises. // The blow given by a light weight becomes powerful, as much as was the power of its cause. That is, an arrow weighs 3 ounces: a force made by a weight of 400 pounds draws the cord of the crossbow up to the nut, and in the releasing that it does, the said force transmutes itself and attaches itself to the arrow. Therefore, although an arrow weighs 3 ounces, it carries with it in its course the nature of as much weight as was its cause. // Every weight driven by violent motion adds to itself, during the flight, as much power as was that of the cause of its course. The weight thrown into the air, the more it is accompanied by what drives it, the longer and swifter its course will be. // The ponderous motions are of 2 natures: one operates attached and joined with its cause ...; the other by long distance entirely separates itself; the first is moved by circular movement, the other by a straight line. // If the weight driven has no proportion with the cause of its flight, its blow is worth nothing. // Every violent motion carries with it the power of its cause. // That blow will be of little value which does not fall at its contact within equal angles. // In movement the thing set going, finding its course broken, damages itself at its contact, and the contact remains damaged in like manner by the supervening blow. Therefore the angular contact receives double violence, and if the blow is acute it will be of great penetration. // What difference is there between force and weight. // Force is a spiritual essence, which by accidental violence is joined in ponderous bodies drawn out of their natural desire, in which, although it lasts little, nonetheless it often appears of marvellous power. // Drawn out of natural rest. // Force is a spiritual power ... // Fo[rce] ... // Force is a spiritual essence, which by accidental violence is joined to ponderous bodies, which are drawn out of their natural desire, in which, although it lives little, nonetheless it is of marvellous power. // Force is a spiritual power, incorporeal and impalpable, which is caused with short life in the bodies that, by accidental violence, stand out of their natural rest, and al[though] ... // Spiritual I say, because in it is invisible life, incorporeal and impalpable, because the body where it is born does not grow either in form or in weight.