Weights also thrown cleave the air and dissipate it, as they fall with force; the air recoiling back, according to its natural tendency to rush in and fill the vacuity, follows the impulse, and accelerates the motion. The fall also of thunderbolts is like to darting any thing. For by the blow in the cloud, the fiery matter exploded breaks into the air; and it being broken gives way, and again being contracted above, by main force it presses the thunderbolt downwards contrary to Nature.