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

9. If equally matched, we can offer battle;

[Li Ch’uan, followed by Ho Shih, gives the following paraphrase: "If attackers and attacked are equally matched in strength, only the able general will fight."] if slightly inferior in numbers, we can avoid the enemy; [The meaning, "we can _watch_ the enemy," is certainly a great improvement on the above; but unfortunately there appears to be no very good authority for the variant. Chang Yu reminds us that the saying only applies if the other factors are equal; a small difference in numbers is often more than counterbalanced by superior energy and discipline.] if quite unequal in every way, we can flee from him.