俱舍論記 5.122

5.122

「彼體一故至無差別故」者，論主作比量破。先舉兩因，後舉宗、喻。彼行體一故，是一因。無障礙故，是第二因。放箭之時往趣餘方，初急、中緩、後至，三時分位差別應不得有，初位之時應當非急，行體一故，如中、後位。中位之時應當非緩，行體一故，如初、後位。後位之時應當不至，行體一故，如初、中位。又破云：後位之時應無墮落，無障礙故，猶如初位。勝論救作不成過：後位墮落由風障礙。若謂由風所障礙故，又破云：此箭初位應當即墮，能障礙風無差別故，猶如後位。此箭後位應無墮落，能障礙風無差別故，猶如初位。

"Because its substance is unitary… because there is no difference" is the author of the treatise formulating an inference (anumāna) to refute them. He first adduces two reasons, and then states the thesis and the examples. That the substance of that velocity is unitary is the first reason. That there is no obstruction is the second reason. When an arrow is released, speeding toward another direction, the difference between the three periods—the initial swiftness, the middle slackening, and the final arrival—should not be possible. At the initial period it should not be swift, because the substance of velocity is unitary, just like in the middle and final periods. At the middle period it should not be slack, because the substance of velocity is unitary, just like in the initial and final periods. At the final period it should not arrive, because the substance of velocity is unitary, just like in the initial and middle periods. Furthermore, he refutes them: At the final period there should be no falling, because there is no obstruction, just like in the initial period. The Vaiśeṣikas attempt a defense by alleging the fallacy of an unestablished reason: the falling in the final period is caused by the obstruction of the wind. If they say it is caused by the obstruction of the wind, he refutes them again: This arrow should fall immediately at the initial period, because the obstructing wind has no difference, just as in the final period. This arrow should have no falling in the final period, because the obstructing wind has no difference, just as in the initial period.