The Art of War by active 6th century B.C. Sunzi

2. In order to carry out an attack, we must have means available.

[T’sao Kung thinks that "traitors in the enemy’s camp" are referred to. But Ch’en Hao is more likely to be right in saying: "We must have favourable circumstances in general, not merely traitors to help us." Chia Lin says: "We must avail ourselves of wind and dry weather."] the material for raising fire should always be kept in readiness. [Tu Mu suggests as material for making fire: "dry vegetable matter, reeds, brushwood, straw, grease, oil, etc." Here we have the material cause. Chang Yu says: "vessels for hoarding fire, stuff for lighting fires."]