Chapter 1, Verses 3 and 4 - Sun Tzu

The art of war, then, is governed by five constant factors, to be taken into account in one's deliberations, when seeking to determine the conditions obtaining in the field. These are: (1) The Moral Law; (2) Heaven; (3) Earth; (4) The Commander; (5) Method and discipline.
~ from The Art of War, Giles translation ~

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