40. To muster his host and bring it into danger: — this may be termed the business of the general.
41. The different measures suited to the nine varieties of ground; the expediency of aggressive or defensive tactics; and the fundamental laws of human nature: these are things that must most certainly be studied.
42. When invading hostile territory, the general principle is, that penetrating deeply brings cohesion; penetrating but a short way means dispersion.
43. When you leave your own country behind, and take your army across neighbouring territory, you find yourself on critical ground.