Chapter 5, Verses 12, 13 and 14 - Sun Tzu

The onset of troops is like the rush of a torrent which will even roll stones along in its course. The quality of decision is like the well-timed swoop of a falcon which enables it to strike and destroy its victim. Therefore the good fighter will be terrible in his onset, and prompt in his decision.
~ from The Art of War, Giles translation ~

Go here to read the introductory post to the verses of The Art of War.